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Volume 15
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Metals, Volume 15, Issue 5 (May 2025) – 31 articles

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22 pages, 4762 KiB  
Article
Research on the Structure and Mechanical Properties of Mesh Powder Composite Copper Microporous Materials
by Liuyang Duan, Zhiwen Zhao and Wuyi Ming
Metals 2025, 15(5), 498; https://doi.org/10.3390/met15050498 (registering DOI) - 29 Apr 2025
Abstract
With the proliferation of flexible electronics, the advancement of mechanically compliant thermal management systems, notably flexible heat pipes, is imperative to address evolving demands for adaptive thermal regulation in deformable device architectures. The wicks of heat pipes commonly utilize porous copper. In this [...] Read more.
With the proliferation of flexible electronics, the advancement of mechanically compliant thermal management systems, notably flexible heat pipes, is imperative to address evolving demands for adaptive thermal regulation in deformable device architectures. The wicks of heat pipes commonly utilize porous copper. In this study, three types of porous copper materials were fabricated: sintered pure copper powder, sintered copper powder with a copper mesh (as a reinforcing network), and sintered copper powder with NaCl (as a pore-forming agent). Their pore structure characteristics, tensile, and compressive mechanical properties were systematically investigated. Results demonstrated that incorporating NaCl into copper powder significantly increased porosity and enlarged pore size, thereby enhancing permeability. For instance, compared to sintered pure copper powder, the addition of NaCl increased the average pore diameter from 0.31 μm to 2.44 μm and improved permeability from 1.908 × 10−14 m2 to 2.832 × 10−12 m2, effectively reducing fluid flow resistance. The introduction of copper mesh notably improved mechanical performance: under a sintering temperature of 900 °C, tensile strength increased from 121.6 MPa to 132.2 MPa, and compressive strength rose from 443.5 MPa to 458.4 MPa. However, NaCl-added porous copper exhibited a drastic decline in tensile strength. Consequently, NaCl-modified porous copper is unsuitable for flexible wick applications, whereas copper mesh-reinforced porous copper shows potential as a flexible wick, though further investigation is required to enhance its permeability mechanisms. Full article
(This article belongs to the Special Issue Microstructural Characteristics and Mechanical Behavior of Particle-Reinforced Copper-Based Composites)
20 pages, 8233 KiB  
Article
Transformation of TiN to TiNO Films via In-Situ Temperature-Dependent Oxygen Diffusion Process and Their Electrochemical Behavior
by Sheilah Cherono, Ikenna Chris-Okoro, Mengxin Liu, R. Soyoung Kim, Swapnil Nalawade, Wisdom Akande, Mihai Maria-Diana, Johannes Mahl, Christopher Hale, Junko Yano, Shyam Aravamudhan, Ethan Crumlin, Valentin Craciun and Dhananjay Kumar
Metals 2025, 15(5), 497; https://doi.org/10.3390/met15050497 (registering DOI) - 29 Apr 2025
Abstract
Titanium oxynitride (TiNO) thin films represent a multifaceted material system applicable in diverse fields, including energy storage, solar cells, sensors, protective coatings, and electrocatalysis. This study reports the synthesis of TiNO thin films grown at different substrate temperatures using pulsed laser deposition. A [...] Read more.
Titanium oxynitride (TiNO) thin films represent a multifaceted material system applicable in diverse fields, including energy storage, solar cells, sensors, protective coatings, and electrocatalysis. This study reports the synthesis of TiNO thin films grown at different substrate temperatures using pulsed laser deposition. A comprehensive structural investigation was conducted by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Non-Rutherford backscattering spectrometry (N-RBS), and X-ray absorption spectroscopy (XAS), which facilitated a detailed analysis that determined the phase, composition, and crystallinity of the films. Structural control was achieved via temperature-dependent oxygen in-diffusion, nitrogen out-diffusion, and the nucleation growth process related to adatom mobility. The XPS analysis indicates that the TiNO films consist of heterogeneous mixtures of TiN, TiNO, and TiO2 phases with temperature-dependent relative abundances. The correlation between the structure and electrochemical behavior of the thin films was examined. The TiNO films with relatively higher N/O ratio, meaning less oxidized, were more electrochemically active than the films with lower N/O ratio, i.e., more oxidized films. Films with higher oxidation levels demonstrated enhanced crystallinity and greater stability under electrochemical polarization. These findings demonstrate the importance of substrate temperature control in tailoring the properties of TiNO film, which is a fundamental part of designing and optimizing an efficient electrode material. Full article
(This article belongs to the Special Issue Feature Paper Collection of “Current Challenges in Corrosion Research" (2nd Edition))
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14 pages, 5879 KiB  
Article
Effect of Post-Weld Heat Treatment Cooling Strategies on Microstructure and Mechanical Properties of 0.3 C-Cr-Mo-V Steel Weld Joints Using GTAW Process
by Syed Quadir Moinuddin, Mohammad Faseeulla Khan, Khaled Alnamasi, Skander Jribi, K. Radhakrishnan, Syed Shaul Hameed, V. Muralidharan and Muralimohan Cheepu
Metals 2025, 15(5), 496; https://doi.org/10.3390/met15050496 - 29 Apr 2025
Abstract
A total of 0.3%C-Cr-Mo-V steel, a high-strength alloy steel widely used in rocket motor housings, suspension systems in high-performance vehicles, etc., is noted due to its high strength-to-weight ratio. However, its high carbon equivalent (CE > 1%) makes it challenging to weld, as [...] Read more.
A total of 0.3%C-Cr-Mo-V steel, a high-strength alloy steel widely used in rocket motor housings, suspension systems in high-performance vehicles, etc., is noted due to its high strength-to-weight ratio. However, its high carbon equivalent (CE > 1%) makes it challenging to weld, as it is prone to brittle martensitic formation, which increases the risk of cracking and embrittlement. The present paper focuses on enhancing the microstructure and mechanical properties of 0.3% C-Cr-Mo-V steel by gas tungsten arc welded (GTAW) joints, utilizing post-weld heat treatment and cooling strategies (PWHTCS). A systematic experimental approach was employed to ensure a defect-free weld through dye penetrant testing (DPT) and X-ray radiography techniques. Subsequently, test specimens were extracted from the welded sections and subjected to PWHT protocols, including hardening, tempering, and rapid quenching using air and oil cooling (AC and OC, respectively) mediums. Results show that OC has enhanced tensile strength and hardness while simultaneously maintaining and improving ductility, ensuring a well-balanced combination of strength and toughness. Fractography analysis revealed ductile fracture in AC samples, whereas OC weldments exhibited a mixed ductile–brittle fracture mode. Thus, the findings demonstrate the critical role of PWHTCS, with OC, as an effective method for achieving enhanced mechanical performance and microstructural stability in high-integrity applications. Full article
(This article belongs to the Special Issue Welding and Joining of Advanced High-Strength Steels (2nd Edition))
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13 pages, 4489 KiB  
Article
A Theoretical Study of Ordinary Dislocations and Order Twinning in γ-TiAl at Finite Temperatures
by Yufeng Wen, Chengchen Jin, Yanlin Yu, Xianshi Zeng, Zhangli Lai, Kai Xiong and Lili Liu
Metals 2025, 15(5), 495; https://doi.org/10.3390/met15050495 - 29 Apr 2025
Abstract
The generalized planar fault energies of 1/2<110] and 1/6<112] slip directions on {111} planes in γ-TiAl at temperatures up to 1500 K were predicted through first-principles calculations and quasi-harmonic approximation. The obtained unstable stacking and twinning fault (USF and UTF) energies, as [...] Read more.
The generalized planar fault energies of 1/2<110] and 1/6<112] slip directions on {111} planes in γ-TiAl at temperatures up to 1500 K were predicted through first-principles calculations and quasi-harmonic approximation. The obtained unstable stacking and twinning fault (USF and UTF) energies, as well as superlattice intrinsic and extrinsic stacking fault (SISF and SESF) energies, are consistent with existing theoretical data. Results show that the USF, UTF, SISF, and SESF energies for both slip directions decrease overall as temperature increases. The effect of temperature on the 1/2<110] ordinary dislocation and 1/6<112] order twinning in γ-TiAl is further analyzed generalized planar fault energies. It is demonstrated that the nucleation of ordinary dislocation and twinning dislocations becomes more favorable with increasing temperature. Furthermore, it is shown that order twinning in γ-TiAl is more likely to occur at crack tips or grain boundaries, and its twinnability is enhanced at elevated temperatures. Full article
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13 pages, 1854 KiB  
Article
Uranium(VI), Thorium(IV), and Lanthanides(III) Extraction from the Eudialyte Concentrate Using the N,O-Hybrid Heterocyclic Reagents
by Alfiya M. Safiulina, Alexey V. Lizunov, Alexey V. Ivanov, Nataliya E. Borisova, Petr I. Matveev, Sergey M. Aksenov and Dmitry V. Ivanets
Metals 2025, 15(5), 494; https://doi.org/10.3390/met15050494 - 29 Apr 2025
Abstract
N,O-donor hybrid heterocyclic extractants have great potential for separation of actinides from lanthanides in spent nuclear fuel reprocessing processes. We demonstrate that this type of reagents can be used for primary concentration of actinides contained in eudialyte, a promising mineral containing a heavy [...] Read more.
N,O-donor hybrid heterocyclic extractants have great potential for separation of actinides from lanthanides in spent nuclear fuel reprocessing processes. We demonstrate that this type of reagents can be used for primary concentration of actinides contained in eudialyte, a promising mineral containing a heavy group of lanthanides. With respect to lanthanide ions, the efficiency of their extraction decreases in the series L3 >> L1 > L2, and the extraction of actinides decreases in the series L1 ≈ L3 >> L2. For the extractant L2 based on 2,2′-bipyridine-6,6′-dicarboxylic acid diamide, the efficiency of lanthanide purification from U, Th exceeds 50. The structure and stereochemical features of the ligands do not have a significant effect on the composition of the formed complexes. The solvation numbers are close to 1 for all range f-elements studied, except for thorium, which indicates the predominant formation of complexes with the composition ratio of 1:1. The solvation numbers 1.4–1.5 are observed for thorium(IV), and the established values indicate the formation of a mixture of complexes with the composition ratios of 1:1 and 2:1. Full article
(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy—3rd Edition)
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12 pages, 14187 KiB  
Article
Composites Cu–Ti3SiC2 Obtained via Extrusion-Based Additive Manufacturing: Structure and Tribological Properties
by Maksim Krinitcyn, Egor Ryumin, Georgy Kopytov and Olga Novitskaya
Metals 2025, 15(5), 493; https://doi.org/10.3390/met15050493 - 28 Apr 2025
Viewed by 46
Abstract
In the present study, composites Cu–Ti3SiC2 were obtained via extrusion-based additive manufacturing technology. The composite was characterized in terms of its structure, mechanical properties, and tribological properties. The use of a low-energy additive manufacturing technique allows for the avoidance of [...] Read more.
In the present study, composites Cu–Ti3SiC2 were obtained via extrusion-based additive manufacturing technology. The composite was characterized in terms of its structure, mechanical properties, and tribological properties. The use of a low-energy additive manufacturing technique allows for the avoidance of the decomposition of the MAX phase while obtaining bulk samples. The optimal composition of 50 vol.% of Ti3SiC2 and 50 vol.% of Cu was selected based on the flow rate of feedstock melt and the density of the samples. The resulting composite exhibited a dense copper matrix with Ti3SiC2 and TiC inclusions, achieving 97% density and 62% IACS electrical conductivity. Tribological tests under varying loads, speeds, and temperatures demonstrated that increasing the load and speed increased the coefficient of friction and the wear rate, while higher temperatures reduced friction due to surface oxidation. Full article
(This article belongs to the Special Issue Additive Manufacturing and Characterization of Metallic Alloys and Composites)
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17 pages, 5007 KiB  
Article
Unveiling High-Pressure Behavior of Sc3AlC MAX Phase: A Comprehensive Theoretical Study on Structural, Mechanical, Dislocation, and Electronic Properties
by Junping Xi, Zhipeng Wang, Linkun Zhang, Li Ma and Pingying Tang
Metals 2025, 15(5), 492; https://doi.org/10.3390/met15050492 - 27 Apr 2025
Viewed by 119
Abstract
The structural, mechanical, dislocation, and electronic properties of the Sc3AlC MAX phase under applied pressure are investigated in detail using first-principles calculations. Key parameters, including lattice parameter ratios, elastic constants, Young’s modulus, bulk modulus, shear modulus, brittle-to-ductile behavior, Poisson’s ratio, anisotropy, [...] Read more.
The structural, mechanical, dislocation, and electronic properties of the Sc3AlC MAX phase under applied pressure are investigated in detail using first-principles calculations. Key parameters, including lattice parameter ratios, elastic constants, Young’s modulus, bulk modulus, shear modulus, brittle-to-ductile behavior, Poisson’s ratio, anisotropy, Cauchy pressure, yield strength, Vickers hardness, and energy factors, are systematically analyzed as a function of applied pressure. The results demonstrate that the Sc3AlC MAX phase exhibits remarkable mechanical stability within the pressure range of 0 to 60 GPa. Notably, applied pressure markedly improves its mechanical properties, such as resistance to elastic, bulk, and shear deformations. The B/G ratio suggests a tendency toward ductile behavior with increasing pressure, and the negative Cauchy pressure indicates the directional characteristics of interatomic bonding in nature. Vickers hardness and yield strength increase under pressures of 0 to 10 GPa and then decrease sharply above 50 GPa. High pressure suppresses dislocation nucleation due to the increased energy factors, along with twinning deformation. Furthermore, electronic structure analysis confirms that high pressure enhances the interatomic bonding in the Sc3AlC MAX phase, while the enhancement effect is not substantial. This study offers critical insights for designing MAX phase materials for extreme environments, advancing applications in aerospace and electronics fields. Full article
(This article belongs to the Special Issue Design and Development of Metal Matrix Composites)
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18 pages, 14294 KiB  
Article
Research on Microstructure and Mechanical Properties of Ultrasonic-Assisted Gas Metal Arc Welding Additive Manufacturing with High-Nitrogen Steel Welding Wire
by Jiawen Luo, Zhizheng He, Zihuan Hua and Chenglei Fan
Metals 2025, 15(5), 491; https://doi.org/10.3390/met15050491 - 27 Apr 2025
Viewed by 75
Abstract
High-nitrogen steels (HNSs) are valued for their superior mechanical strength and corrosion resistance, making them ideal for high-end industrial applications. However, nitrogen loss during gas metal arc welding additive manufacturing (GMAW-AM) often results in porosity and coarse microstructures, degrading component performance. This study [...] Read more.
High-nitrogen steels (HNSs) are valued for their superior mechanical strength and corrosion resistance, making them ideal for high-end industrial applications. However, nitrogen loss during gas metal arc welding additive manufacturing (GMAW-AM) often results in porosity and coarse microstructures, degrading component performance. This study introduces a coaxial ultrasonic-assisted GMAW-AM (U-GMAW-AM) process to mitigate nitrogen loss and refine the microstructure. Welding wires with 0.35 wt.% and 0.70 wt.% nitrogen were used to examine the effects of welding voltage (24.5–30 V) and ultrasonic power (0–2 kW). The results show that a higher voltage increases nitrogen evaporation, with a maximum loss of 0.22% at 30 V. In contrast, ultrasonic assistance reduces nitrogen loss by up to 29.17% for the 0.70 wt.% wire. Microstructural analysis reveals a significant reduction in ferrite and enhanced austenite formation due to better nitrogen retention. Mechanical testing shows that ultrasonic assistance improves tensile strength by 100 MPa (up to 919.1 MPa), elongation by nearly 10%, and hardness uniformity. These findings highlight the potential of ultrasonic assistance for optimizing high-nitrogen steel properties in additive manufacturing. Full article
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17 pages, 20034 KiB  
Article
Effect of Nb Content on Strength and Toughness of 25MnB Crawler Steel and Its Microstructural Characterization
by Zixun He, Jianjing Wang, Houxin Wang, Yajie Cui, Zhengbing Meng, Jiangbo Deng, Meiqiao Wu, Chaoyang Zhou and Xinbin Liu
Metals 2025, 15(5), 490; https://doi.org/10.3390/met15050490 - 26 Apr 2025
Viewed by 125
Abstract
To address the failure of 25MnB crawler track steel due to insufficient strength and toughness, this study designed a new type of 25MnB crawler track steel and investigated the effects of the Nb content on its mechanical properties, microstructure, dislocation evolution, and precipitation [...] Read more.
To address the failure of 25MnB crawler track steel due to insufficient strength and toughness, this study designed a new type of 25MnB crawler track steel and investigated the effects of the Nb content on its mechanical properties, microstructure, dislocation evolution, and precipitation behavior. The experimental results show that, compared to 25MnB steel without Nb, the addition of 0.03% Nb significantly increased the yield strength of the experimental steel to 1450 MPa, with an elongation rate of 15.9%. The room-temperature impact energy showed a slight improvement, while the low-temperature impact absorption energy improved notably, reaching 36 J at −40 °C. The microstructural characterization and analysis revealed that increasing the Nb content refined the effective grain size of prior austenite and martensite. The (Nb, Ti)C precipitates provided a higher precipitation driving force, promoting the formation of precipitates and increasing the average dislocation density. Additionally, the increased proportion of high-angle grain boundaries (HAGBs) enabled grain boundaries and precipitates to jointly hinder crack propagation. This study demonstrates that Nb-Ti microalloying can effectively enhance the strength, toughness, and plasticity of track steel, demonstrating promising application prospects. Full article
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14 pages, 5677 KiB  
Article
Solidification Window in Al-Based Casting Alloys
by Simone Ferraro, Mauro Palumbo, Marcello Baricco and Alberto Castellero
Metals 2025, 15(5), 489; https://doi.org/10.3390/met15050489 (registering DOI) - 26 Apr 2025
Viewed by 155
Abstract
Semi-solid processes of aluminium alloys, characterised by the coexistence of solid and liquid phases, offer advantages in terms of mechanical properties and fatigue resistance, thanks to the more globular microstructure. Thermodynamic models can be used to analyse the solidification behaviour and to predict [...] Read more.
Semi-solid processes of aluminium alloys, characterised by the coexistence of solid and liquid phases, offer advantages in terms of mechanical properties and fatigue resistance, thanks to the more globular microstructure. Thermodynamic models can be used to analyse the solidification behaviour and to predict the solidification window, ΔT. The CALPHAD method enables the calculation of the phases formed during solidification and the optimisation of alloy composition to meet specific industrial requirements. This study aims to assess how thermodynamic properties in both liquid and solid phases affect the ΔT. Initially, the influence of thermodynamic properties of pure components and interaction parameters was analysed in simplified regular binary systems. To compare these findings with real industrial systems, Al-based alloys were examined. Using available databases, the ΔT was estimated via the CALPHAD method adding alloying elements commonly found in secondary Al-alloys. Finally, the same minority alloying elements were added to Al-Si 8 and 11 wt.% alloys, and the corresponding ΔT were calculated. Cr, Fe, Mg, Mn, and Ti increase the ΔT, while Cu, Ni, and Zn decrease it. The obtained results may serve as a valuable tool for interpreting phenomenological observations and understanding the role of minority elements in the semi-solid processing of secondary Al-Si casting alloys. Full article
(This article belongs to the Special Issue Solidification and Phase Transformation of Light Alloys)
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46 pages, 18469 KiB  
Review
Optimising Additive Manufacturing of NiTi and NiMnGa Shape Memory Alloys: A Review
by Ali Ramezannejad, Daniel East, Anthony Bruce Murphy, Guoxing Lu and Kun Vanna Yang
Metals 2025, 15(5), 488; https://doi.org/10.3390/met15050488 - 25 Apr 2025
Viewed by 97
Abstract
NiTi and NiMnGa stand out as prime thermal and magnetic shape memory alloys (SMAs), possessing a superior shape memory effect (SME) and superelasticity (SE). These alloys have crucial current and potential future applications across industries. Additive manufacturing (AM) offers a transformative approach to [...] Read more.
NiTi and NiMnGa stand out as prime thermal and magnetic shape memory alloys (SMAs), possessing a superior shape memory effect (SME) and superelasticity (SE). These alloys have crucial current and potential future applications across industries. Additive manufacturing (AM) offers a transformative approach to fabricating these materials into complex geometries; however, the quest to create integral additively manufactured structures with reliable thermal or magnetic shape memory properties remains a recent and fast-emerging research frontier. This article provides a comprehensive review on (i) the intricate principles giving rise to the thermal SME and SE in NiTi, and the magnetic SME in NiMnGa alloys, emphasising their specific relevance in the realm of AM, and (ii) the latest developments, recent findings, and ongoing challenges in the AM of NiTi- and NiMnGa-based SMAs, including their functional lattice structures. Based on this review, for the first time, novel, empirically derived AM process design maps tailored to maximise SME and SE in laser powder bed fusion- and directed-energy deposition-processed NiTi structures are proposed. Similarly, promising avenues to resolve the key challenges regarding the AM of NiMnGa magnetic SMAs are suggested. This article concludes by outlining the most promising future research directions shaping the trajectory of AM of these SMAs. Full article
(This article belongs to the Special Issue Recent Developments in Laser Additive Manufacturing of Metallic Materials)
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20 pages, 5380 KiB  
Article
Machine Learning-Enabled Prediction and Mechanistic Analysis of Compressive Yield Strength–Hardness Correlation in High-Entropy Alloys
by Haiyu Wan, Baobin Xie, Hui Feng and Jia Li
Metals 2025, 15(5), 487; https://doi.org/10.3390/met15050487 - 25 Apr 2025
Viewed by 108
Abstract
High-entropy alloys (HEAs) represent a paradigm-shifting material system offering vast compositional space for tailoring mechanical properties. The yield strength and hardness are critical performance metrics, yet their interrelationships in diverse HEAs remain incompletely understood, partly due to data limitations. This work employs an [...] Read more.
High-entropy alloys (HEAs) represent a paradigm-shifting material system offering vast compositional space for tailoring mechanical properties. The yield strength and hardness are critical performance metrics, yet their interrelationships in diverse HEAs remain incompletely understood, partly due to data limitations. This work employs an integrated machine learning framework to investigate the compressive yield strength (σy) and hardness (HV) correlation across a dataset of cast HEAs. Random forest models are successfully developed for phase structure classification (accuracy = 92%), hardness prediction (test R2 = 0.90), and yield strength prediction (test R2 = 0.91), enabling data imputation to expand the analysis dataset. Correlation analysis on the expanded dataset reveals a general positive trend between σy and HV (overall Pearson r = 0.75) but highlights a strong dependence on the predicted phase structure. The single-phase BCC alloys exhibit the strongest linear correlation between σy and HV (r = 0.88), whereas the single-phase FCC alloys show a weaker linear dependence (r = 0.59), and multiphase alloy systems display varied behavior. The specific ranges of compositional parameters (highly negative mixing enthalpy ΔH, low atomic size difference δ, high mixing entropy ΔS, and intermediate-to-high valence electron concentration VEC) are associated with a stronger σy-HV correlation, potentially linked to the formation of stable solid solutions. Furthermore, artificial neural network modeling confirms the varying complexity of the σy-HV relationship across different phases, outperforming simple models for some multiphase systems. This work provides robust predictive models for HEA properties and advances the fundamental understanding of the composition- and phase-dependent coupling between yield strength and hardness, aiding rational HEA design. Full article
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21 pages, 19235 KiB  
Article
Insight to the Microstructure Analysis of a HP Austenitic Heat-Resistant Steel Under Short-Term High-Temperature Exposure
by Milica Timotijević, Olivera Erić Cekić, Petar Janjatović, Aleksandar Kremenović, Milena Rosić, Srecko Stopic and Dragan Rajnović
Metals 2025, 15(5), 486; https://doi.org/10.3390/met15050486 - 25 Apr 2025
Viewed by 128
Abstract
The HP40Nb alloy, commonly used in the petrochemical industry as a heat-resistant material, undergoes significant microstructural changes at high temperatures. This study examined samples from the HP40Nb radiant tube used in a reformer furnace, exposed to 950, 1050, and 1150 °C for 2 [...] Read more.
The HP40Nb alloy, commonly used in the petrochemical industry as a heat-resistant material, undergoes significant microstructural changes at high temperatures. This study examined samples from the HP40Nb radiant tube used in a reformer furnace, exposed to 950, 1050, and 1150 °C for 2 and 8 h. Metallographic analysis, including optical microscopy, SEM, EDS, and XRPD, revealed that the as-cast alloy has an austenitic dendritic matrix with primary eutectic-like carbides (M23C6 and MC types). Prolonged exposure to high temperatures transformed the primary carbides into coarse M23C6 forms, losing their lamellar shape. The number of secondary carbides decreased with increasing temperature, and at 1150 °C for 480 min, secondary Cr23C6 carbides nearly decomposed, and Nb carbides dissolved into the austenitic matrix. Full article
(This article belongs to the Special Issue Novel Insights and Advances in Steels and Cast Irons)
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16 pages, 7457 KiB  
Article
Stress Determination by IHD in Additively Manufactured Austenitic Steel Samples: A Validation Study
by João Paulo Nobre, Maria José Marques and António Castanhola Batista
Metals 2025, 15(5), 485; https://doi.org/10.3390/met15050485 - 25 Apr 2025
Viewed by 119
Abstract
The present work aims to verify whether the incremental hole-drilling technique (IHD), a widely accepted technique, is suitable for determining residual stresses in AISI 316L samples obtained by selective laser melting (SLM). The thermo-mechanical effects of cutting during the application of this technique [...] Read more.
The present work aims to verify whether the incremental hole-drilling technique (IHD), a widely accepted technique, is suitable for determining residual stresses in AISI 316L samples obtained by selective laser melting (SLM). The thermo-mechanical effects of cutting during the application of this technique can induce unwanted residual stresses due to the relatively low thermal conductivity of this material, leading to erroneous results. To accomplish this aim, a hybrid experimental-numerical method was implemented to analyze the ability of IHD to determine an imposed stress state. Experimentally, samples were subjected to a tensile calibration stress using a horizontal tensile test machine. To eliminate pre-existing residual stress, the samples were subjected to differential loads, instead of absolute ones. In this way, experimental strain-depth relaxation curves related to the imposed calibration stress were obtained. Based on the experimental data, IHD was numerically simulated using the finite element method. Numerical strain-depth relaxation curves, related to the same calibration stress used in the experimental study, were obtained. The comparison between the experimental and numerical strain-depth relaxation curves, as well as the stresses calculated using the so-called integral method for determining stresses via IHD, shows that IHD is a suitable technique for measuring residual stresses in additively manufactured AISI 316L samples. Full article
(This article belongs to the Special Issue Surface Integrity and Functional Performance Induced by Hybrid Processing of Metallic Alloys)
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17 pages, 15675 KiB  
Article
The Role of Si Element on the Precipitation Behavior of GH2907 Superalloys
by Mengxuan Li, Jianping Wan, Zuojun Ding and Rengeng Li
Metals 2025, 15(5), 484; https://doi.org/10.3390/met15050484 - 25 Apr 2025
Viewed by 117
Abstract
GH2097, a Fe-Ni-Co-based superalloy extensively employed in high-temperature critical components such as aircraft engines, was investigated to elucidate the influence of Si content on its precipitation behavior and mechanical properties. By systematically adjusting Si concentrations, it was demonstrated that Si significantly modulates the [...] Read more.
GH2097, a Fe-Ni-Co-based superalloy extensively employed in high-temperature critical components such as aircraft engines, was investigated to elucidate the influence of Si content on its precipitation behavior and mechanical properties. By systematically adjusting Si concentrations, it was demonstrated that Si significantly modulates the size, distribution, and stability of γ′ phase (Ni3TiNb). As Si content increases, γ′ phase coarsening (mean size: 30.1→40.3 nm) results in a marginal increase in volume fraction of 2%. Mechanical testing revealed a direct correlation between Si content and yield strength enhancement, achieving a maximum increment of 97.1 MPa. Post solution-aging treatment, γ′ strengthening dominated the strengthening mechanisms in GH2097, contributing over 50% to the overall strength. Microstructural characterization (SEM/TEM) further confirmed that optimal Si addition balances precipitation kinetics and grain boundary stabilization without inducing detrimental phases. Therefore, it is important to consider the role of the Si element in the microstructure control of GH2907 alloy. Full article
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12 pages, 2287 KiB  
Article
Fracturing in 14MoV6-3 Steel Weld Joints—Including Base Metals—After a Short Time in Service
by Esmail Ali Salem Ahmed, Nenad Radović, Dragomir Glišić, Stefan Dikić, Nikola Milovanović, Mirjana Opačić and Jasmina Lozanović
Metals 2025, 15(5), 483; https://doi.org/10.3390/met15050483 - 25 Apr 2025
Viewed by 122
Abstract
In order to establish the influence of prolonged exposure to high temperatures on 14MoV6-3 steel, three different weld joints were designed. New-to-new material, new-to-used material, and used-to-used material joints were welded using two welding technologies—GTAW and a combination of GTAW + MMA. The [...] Read more.
In order to establish the influence of prolonged exposure to high temperatures on 14MoV6-3 steel, three different weld joints were designed. New-to-new material, new-to-used material, and used-to-used material joints were welded using two welding technologies—GTAW and a combination of GTAW + MMA. The weldments were tested by means of microstructure and tensile testing. The results showed that in all weldments, a fracture occurred in the base metal. Also, in the case of the new-to-used welded sample, the fracture always occurred in the used base metal. Since both materials have the same chemical composition, the difference in microstructure was related to long exposure to high temperatures. New steel has a considerably smaller grain size, while the used material underwent grain growth coupled with carbide coarsening, which decreased its strength. The yield strength (YS) of the new material was higher than the YS of the used material, which exhibited similar values in the used base metal and both weldments. It can be assumed that, since deformation starts in the area with the lowest yield point, the used material is the critical place in a given weldment. Therefore, the accurate extent of strength decrease cannot be evaluated based on the testing of new material, i.e., there is a need to reconsider the traditional qualifications of welding technology. Full article
(This article belongs to the Special Issue Fracture Mechanics and Failure Analysis of Metallic Materials)
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17 pages, 8805 KiB  
Article
Microstructure and Mechanical Properties of Brass-Clad Copper Stranded Wires in High-Speed Solid/Liquid Continuous Composite Casting and Drawing
by Yu Lei, Xiao Liu, Yanbin Jiang, Fan Zhao, Xinhua Liu and Jianxin Xie
Metals 2025, 15(5), 482; https://doi.org/10.3390/met15050482 - 24 Apr 2025
Viewed by 116
Abstract
A solid/liquid continuous composite casting technology was developed to produce brass-clad copper stranded wire billets efficiently with continuous casting speeds ranging from 200 mm/min to 1000 mm/min. As the casting speed increased, the microstructure of the brass cladding transformed at an angle to [...] Read more.
A solid/liquid continuous composite casting technology was developed to produce brass-clad copper stranded wire billets efficiently with continuous casting speeds ranging from 200 mm/min to 1000 mm/min. As the casting speed increased, the microstructure of the brass cladding transformed at an angle to the radial direction. The wire billet prepared at a casting speed of 600 mm/min was then subjected to drawing. As the percentage reduction in area of the billet increased from 11.9 to 81.5% during the drawing process, the tensile strength improved from 336 MPa to 534 MPa, while the elongation after fracture decreased from 30.1 to 4.7%. Meanwhile, dislocation, dislocation cells, and microbands successively formed in the pure copper strand wires, while twins, shear bands, dislocation pile-ups, and secondary twins gradually formed in the brass cladding. During the drawing process, the interface between copper and brass remained metallurgically bonded, exhibiting coordinated deformation behavior. This paper clarified the evolution of microstructure and mechanical properties of brass-clad copper stranded wires in high-speed solid/liquid continuous composite casting and drawing, which could provide important reference for industrial production. Full article
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19 pages, 2911 KiB  
Article
Numerical Simulation of the Effect of Pre-Strain on Fatigue Crack Growth in AA2024-T351
by Diogo M. Neto, Edmundo Sérgio, André Agra and Fernando V. Antunes
Metals 2025, 15(5), 481; https://doi.org/10.3390/met15050481 - 24 Apr 2025
Viewed by 80
Abstract
The objective here is to study the effect of pre-strain on fatigue crack growth (FCG) in 2024-T351 aluminum alloy. Three pre-strain conditions were considered: without pre-strain, compressive and tensile permanent pre-strains of 4%. A numerical approach based on cumulative plastic strain at the [...] Read more.
The objective here is to study the effect of pre-strain on fatigue crack growth (FCG) in 2024-T351 aluminum alloy. Three pre-strain conditions were considered: without pre-strain, compressive and tensile permanent pre-strains of 4%. A numerical approach based on cumulative plastic strain at the crack tip was followed to predict FCG rate. The compressive pre-strain increased FCG rate, while the tensile pre-strain reduced the da/dN relative to the situation without pre-strain. The influence of pre-strain was linked with plasticity-induced crack closure. In fact, a linear trend was obtained between da/dN and ΔKeff for three crack lengths (a = 16.184; a = 15.048 mm and a = 15.152 mm) and three pre-strain conditions. The increase in the stress ratio from R = 0.1 to R = 0.5 and the elimination of the contact of crack flanks significantly reduced the effect of pre-strain, also pointing to the huge relevance of crack closure in this context. Finally, the effect of pre-strain on da/dN after an overload was also explained by crack closure variations. Full article
(This article belongs to the Section Metal Failure Analysis)
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15 pages, 3705 KiB  
Article
Prediction of Enthalpy of Mixing of Binary Alloys Based on Machine Learning and CALPHAD Assessments
by Shuangying Huang, Guangyu Wang and Zhanmin Cao
Metals 2025, 15(5), 480; https://doi.org/10.3390/met15050480 - 24 Apr 2025
Viewed by 141
Abstract
The enthalpy of mixing, a critical thermodynamic property in the liquid phase reflecting element interaction strength and pivotal for studying phase equilibria, can now be predicted efficiently using machine learning. This study proposes a model combining machine learning with the Calculation of Phase [...] Read more.
The enthalpy of mixing, a critical thermodynamic property in the liquid phase reflecting element interaction strength and pivotal for studying phase equilibria, can now be predicted efficiently using machine learning. This study proposes a model combining machine learning with the Calculation of Phase Diagram (CALPHAD) to predict the enthalpy of mixing. We obtained data for 583 binary alloy systems from the SGTE database, ensuring experimental constraints for accuracy. Using pure element properties and Miedema’s model parameters as descriptors, we trained and evaluated four machine learning algorithms, finding LightGBM to perform best (R2 = 92.2%, MAE = 3.5 kJ/mol). The model performance was further optimized through Recursive Feature Elimination (RFE) and Maximal Information Coefficient (MIC) feature selection methods. Shapley Additive Explanations reveals that the primary factors affecting the mixing enthalpy, such as atomic radius and electronegativity, align with the key parameters of the Miedema model, thereby confirming the physical interpretability of our data-driven approach. This work offers an accelerated method for predicting complex multi-component system thermodynamics. Future research will focus on collecting more high-quality data to enhance model accuracy and generalization. Full article
(This article belongs to the Special Issue Machine Learning in Metallic Materials Processing and Optimizing)
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45 pages, 60152 KiB  
Article
Realization of a Novel FeSiAlCuSn Multicomponent Alloy and Characterization of Intermetallic Phases Formed at Different Temperatures During Cooling
by Pradeep Padhamnath, Filip Kuśmierczyk, Mateusz Kopyściański, Łukasz Gondek, Piotr Migas and Mirosław Karbowniczek
Metals 2025, 15(5), 479; https://doi.org/10.3390/met15050479 - 24 Apr 2025
Viewed by 74
Abstract
Ferrosilicon (FeSi) is a commercially important material with multiple uses in metallurgical processes. Recently, in an attempt to reduce the carbon impact of the FeSi production process, researchers have proposed using recycled Si recovered from electronic waste in the production of FeSi. However, [...] Read more.
Ferrosilicon (FeSi) is a commercially important material with multiple uses in metallurgical processes. Recently, in an attempt to reduce the carbon impact of the FeSi production process, researchers have proposed using recycled Si recovered from electronic waste in the production of FeSi. However, Si recovered from electronic waste usually contains Al, Cu, and Sn as impurities. Hence, FeSi alloys produced with recycled Si from electronic waste may contain all these elements in varying proportions. Al, Cu, and Sn have been explored as alloying elements to produce alloys with Fe. FeSiAl alloys have also been studied recently for their superior properties. In this work, a multicomponent FeSiAlCuSn alloy is produced, and the phases formed at different temperatures are analyzed using different phase identification techniques. We also analyze the hardness of the multicomponent alloy to find any deviation from the standard FeSi alloy without the additional alloying elements. Understanding the phases and the composition of such alloys may help design future multi-component or high-entropy alloys involving Fe, Si, Al, Cu, and Sn for specific applications. Full article
(This article belongs to the Special Issue Processing Technology and Properties of Light Metals)
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15 pages, 5235 KiB  
Article
Sb2S3/Sb2O3 Heterojunction for Improving Photoelectrochemical Properties of Sb2S3 Thin Films
by Honglei Tan, Jia Yang, Zhaofeng Cui, Renjie Tan, Teng Li, Baoqiang Xu, Shaoyuan Li and Bin Yang
Metals 2025, 15(5), 478; https://doi.org/10.3390/met15050478 - 24 Apr 2025
Viewed by 129
Abstract
We prepared antimony metal films via electrodeposition, followed by the synthesis of Sb2S3 films through a chemical vapor phase reaction. Finally, an Sb2O3 film was deposited onto the Sb2S3 film using a chemical bath [...] Read more.
We prepared antimony metal films via electrodeposition, followed by the synthesis of Sb2S3 films through a chemical vapor phase reaction. Finally, an Sb2O3 film was deposited onto the Sb2S3 film using a chemical bath method, successfully constructing a heterojunction photocathode of Sb2S3/Sb2O3; the synthesized Sb2S3/Sb2O3 heterojunction is classified as a Type I heterostructure. The resulting Sb2S3/Sb2O3 heterojunction exhibited a photocurrent density of −0.056 mA cm−2 at −0.15 V (vs. RHE), which is 1.40 times higher than that of Sb2S3 alone under simulated solar illumination. Additionally, the Sb2S3/Sb2O3 heterojunction demonstrated a lower carrier recombination rate and a faster charge transfer rate compared to Sb2S3, as evidenced by photoluminescence and electrochemical impedance spectroscopy tests. For these reasons, the Sb2S3/Sb2O3 heterojunction obtained a hydrogen precipitation rate of 0.163mL cm−2 h−1, which is twice the hydrogen precipitation rate of Sb2S3, under the condition of 60 min of light exposure. The significant enhancement in photoelectrochemical performance is attributed to the formation of the Sb2S3/Sb2O3 heterojunction, which improves both carrier separation and charge transfer efficiency. This heterojunction strategy holds promising potential for visible light-driven photoelectrochemical water splitting. Full article
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18 pages, 3675 KiB  
Article
Experimental Investigation and Optimization of Tool Life in High-Pressure Jet-Assisted Turning of Inconel 718
by Davorin Kramar and Djordje Cica
Metals 2025, 15(5), 477; https://doi.org/10.3390/met15050477 - 23 Apr 2025
Viewed by 98
Abstract
The application of high-pressure jet-assisted (HPJA) machining can increase tool life during machining, as the cutting fluid penetrates better into the interfaces between the tool and the workpiece. In this work, tool life in semi-finish turning of Inconel 718 with coated carbide tools [...] Read more.
The application of high-pressure jet-assisted (HPJA) machining can increase tool life during machining, as the cutting fluid penetrates better into the interfaces between the tool and the workpiece. In this work, tool life in semi-finish turning of Inconel 718 with coated carbide tools and a high-pressure coolant supply is investigated. In a preliminary experiment, tool life was compared between conventional flooding and HPJA machining. The results show tool life that is more than twice as long with HPJA at higher cutting speeds. In the main experiment, tool life was investigated as a function of various high-pressure-jet parameters (nozzle diameter, distance between the point of impact of the jet and the cutting edge and pressure of the jet) and basic cutting parameters (cutting speed and feed rate). The relationship between the above-mentioned process parameters and tool life was analyzed and modeled using response surface methodology (RSM). Analysis of variance (ANOVA) was performed to evaluate the statistical significance of each process parameter for the response. The results revealed that cutting speed is the most important factor for maximizing tool life, followed by pressure of the jet and feed rate. In addition, optimization using the biogeographic optimization (BBO) algorithm was performed and validated in this study. The results of the confirmation experiments show that the proposed optimization method is very effective and results in approximately 8.4% longer tool life compared to the best trial results. Full article
(This article belongs to the Special Issue Surface Integrity and Functional Performance Induced by Hybrid Processing of Metallic Alloys)
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24 pages, 7632 KiB  
Article
Quantitative Microstructure of Multiphase Al-Zn-Si-(Mg) Coatings and Their Effects on Sacrificial Protection for Steel
by Guilherme Adinolfi Colpaert Sartori, Blandine Remy, Tiago Machado Amorim and Polina Volovitch
Metals 2025, 15(5), 476; https://doi.org/10.3390/met15050476 - 23 Apr 2025
Viewed by 130
Abstract
A new combined analysis of SEM-BSE and EDX images using AphelionTM software was proposed to describe the quantitative microstructure (quantity and neighborhood of sacrificial phases) of Al-Zn-Si-(Mg) coatings on steel. Three materials with different Al/Zn ratios and Mg content were analyzed. The [...] Read more.
A new combined analysis of SEM-BSE and EDX images using AphelionTM software was proposed to describe the quantitative microstructure (quantity and neighborhood of sacrificial phases) of Al-Zn-Si-(Mg) coatings on steel. Three materials with different Al/Zn ratios and Mg content were analyzed. The quantitative microstructure allowed us to describe their corrosion behaviors in a chloride environment and understand their ranking for sacrificial protection of steel in accelerated corrosion tests. For the analyses, interdendritic Zn-rich or Mg-rich phases were expected to be more sacrificial to steel than Al-rich dendrites. Without Mg (AZ coating), Al-rich dendrites created a percolating network, but interdendritic phases did not, suggesting their sacrificial protection to steel to be very limited. Additionally, significant Zn gradients inside dendrites led to a premature coating consumption on the surface, creating new zones of naked steel. In the coatings with Mg (AZM), sacrificial interdendritic phases created a percolating network, which is expected to improve long-time sacrificial protection and contribute to a more uniform formation of Zn corrosion products. For Al content between 30 wt.% and 45 wt.%, a lowering of the Al/Zn ratio (L-AZM) increased the connectivity of the sacrificial interdendritic phases, which is expected to improve the long-term sacrificial effect. Accelerated corrosion tests of scratches in the steel coatings validated the hypotheses. Full article
(This article belongs to the Section Corrosion and Protection)
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21 pages, 11678 KiB  
Article
Finite Element Simulation and Process Analysis for Hot-Forming WE43 Magnesium Alloy Fasteners: Comparison of Crystal Plasticity with Traditional Method
by Anqi Jiang, Yuanming Huo, Zixin Zhou, Zhenrong Yan and Yue Sun
Metals 2025, 15(5), 475; https://doi.org/10.3390/met15050475 - 23 Apr 2025
Viewed by 223
Abstract
The WE43 magnesium alloy has gained attention in orthopedic implants due to its biodegradable properties, particularly for fabricating degradable fasteners. However, research on its hot-forming processes remains limited, primarily focusing on macroscopic finite element mechanical analyses. This study introduces a simplified high-temperature upsetting [...] Read more.
The WE43 magnesium alloy has gained attention in orthopedic implants due to its biodegradable properties, particularly for fabricating degradable fasteners. However, research on its hot-forming processes remains limited, primarily focusing on macroscopic finite element mechanical analyses. This study introduces a simplified high-temperature upsetting process and employs a mesoscale crystal plasticity finite element method to model the thermoforming behavior of WE43 fasteners for the first time. Comparative analyses with conventional finite element methods reveal that the crystal plasticity finite element method effectively captures the influence of microstructural evolution on macroscopic deformation. Additionally, temperature effects (25–650 °C) on mechanical performance were systematically evaluated. The results demonstrate that temperatures between 350 °C and 450 °C optimize formability, balancing thermal softening and strain hardening. The crystal plasticity finite element method framework provides enhanced predictive accuracy for micro–macro interactions, offering critical insights for designing biodegradable magnesium alloy implants. Full article
(This article belongs to the Special Issue Modeling, Simulation and Experimental Studies in Metal Forming)
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16 pages, 5388 KiB  
Article
Effects of Composition on Melt Fillability and Impact Resistance of TiAl Alloys for Thin-Blade Turbine Wheels: Laboratory Predictions and Product Verification
by Toshimitsu Tetsui, Yu-Yao Lee, Thomas Vaubois and Pierre Sallot
Metals 2025, 15(5), 474; https://doi.org/10.3390/met15050474 - 22 Apr 2025
Viewed by 138
Abstract
Scaling up the production of TiAl turbine wheels for passenger car turbochargers requires the fabrication of thin blades that are similar to those of nickel-based superalloys. To achieve this, the molten metal fillability and impact resistance of thin blades must be improved. In [...] Read more.
Scaling up the production of TiAl turbine wheels for passenger car turbochargers requires the fabrication of thin blades that are similar to those of nickel-based superalloys. To achieve this, the molten metal fillability and impact resistance of thin blades must be improved. In this study, the effects of composition on these properties are predicted using simple laboratory experiments with binary, ternary, and practical alloys and are then verified with actual turbine wheels. The melt fillability of the turbine wheel blade is predicted using the amount of molten metal passing through an Al2O3-1%SiO2 mesh. The binary alloy exhibits the best fillability, which is reduced by the addition of Cr and Si. Charpy impact tests on as-cast materials at 25 and 850 °C show that the addition of Cr and Mn improves the impact resistance, but the addition of Nb, W, Mo and Si reduces it. Therefore, the molten metal fillability and/or impact resistance of practical TiAl alloys containing such additives owing to other requirements are low and require improvement for use in thin-blade turbine wheel applications. Full article
(This article belongs to the Special Issue Properties, Microstructure and Forming of Intermetallics)
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13 pages, 10824 KiB  
Article
Study of the Surface Structural Transformation and Mechanical Properties of 65Mn Steel Modified by Pulsed Detonation–Plasma Technology
by Youxing He, Mingming Zhang, Xuebing Yang, Wenfu Chen and Lei Lu
Metals 2025, 15(5), 473; https://doi.org/10.3390/met15050473 - 22 Apr 2025
Viewed by 179
Abstract
Pulsed detonation–plasma technology (PDT) is a surface-modification technology used in an atmospheric environment, where plasma, a detonation impact and thermal conditions are combined and have an effect on the material’s surface. In this study, annealed 65Mn steel was selected to further study the [...] Read more.
Pulsed detonation–plasma technology (PDT) is a surface-modification technology used in an atmospheric environment, where plasma, a detonation impact and thermal conditions are combined and have an effect on the material’s surface. In this study, annealed 65Mn steel was selected to further study the principle of PDT modification. The results show that the modified layer with fine grains was divided into an infiltration layer with a large amount of non-uniformly distributed granular CW3 carbides and a heat-affected layer below the infiltration layer after PDT treatment. However, a higher amount of acicular martensite and a lower amount of austenite was achieved in the modified layer, containing a large number of small-angle grain boundaries, dislocations, and twin grains. After the PDT treatment, the hardness of the modified layer, heat-affected layer, and substrate was 980 HV, 856.2 HV, and 250 HV, respectively. The mass loss of the sample before and after PDT treatment was 21.1 mg and 12.4 mg, respectively. The hardness and wear resistance of the modified layer were greatly improved compared with the substrate because of the combined effect of the solid-phase transformation, element infiltration, and distortion. Full article
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13 pages, 9762 KiB  
Article
Fatigue Damage Assessment in AL6XN Stainless Steel Based on the Strain-Hardening Exponent n-Value
by Donovan Ramírez-Acevedo, Ricardo Rafael Ambriz, Christian Jesús García, Cesar Mendoza Gómora and David Jaramillo
Metals 2025, 15(5), 472; https://doi.org/10.3390/met15050472 - 22 Apr 2025
Viewed by 123
Abstract
The fatigue life curve was determined for the AL6XN stainless steel under strain-controlled Low Cycle Fatigue (LCF) tests. Additionally, a specific number of loading cycles were applied to new specimens made from the same AL6XN alloy batch to set an Accumulated Fatigue Damage [...] Read more.
The fatigue life curve was determined for the AL6XN stainless steel under strain-controlled Low Cycle Fatigue (LCF) tests. Additionally, a specific number of loading cycles were applied to new specimens made from the same AL6XN alloy batch to set an Accumulated Fatigue Damage (AFD) based on the Palmgren–Miner rule. The AFD was 0.25, 0.50 and 0.75; subsequently, these specimens were subjected to tensile tests. It was observed that all AFD specimens exhibited a yield strength increment with respect to the AL6XN material property, thus, it was similar to a strain-hardening mechanism. However, the stress–strain behavior and microstructure characterization showed a microvoid nucleation and growth mechanism that competed against the strain-hardening one. The fracture in the 0.75 AFD specimens was dominated by this microvoid-based mechanism. The experimental results indicated that the strain-hardening exponent (n-value) and electrical resistivity (ρ-value) were consistently modified by the AFD in all the specimens, with an inverse linear relationship for the n-value and a nonlinear increasing behavior for the ρ-value. Full article
(This article belongs to the Special Issue Fatigue of Metals and Welded Joints)
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25 pages, 14859 KiB  
Article
The Effect of Drag Finishing on Additively Manufactured Customized Dental Crowns
by Cosmin Cosma, Martin Melichar, Stelian Libu, Alexandru Popan, Glad Contiu, Cristina Teusan, Petru Berce and Nicolae Balc
Metals 2025, 15(5), 471; https://doi.org/10.3390/met15050471 - 22 Apr 2025
Viewed by 212
Abstract
Cobalt–chromium (CoCr) alloys are frequently used to produce customized dental applications such as crowns, bridges, or prostheses. These medical products have anatomical forms, and can be effectively manufactured using the laser-based powder bed fusion (PBF-LB/M) technique. A major disadvantage of this approach is [...] Read more.
Cobalt–chromium (CoCr) alloys are frequently used to produce customized dental applications such as crowns, bridges, or prostheses. These medical products have anatomical forms, and can be effectively manufactured using the laser-based powder bed fusion (PBF-LB/M) technique. A major disadvantage of this approach is the extended time required to refine the resultant surface. The purpose of this research is to reduce the surface roughness of PBF-LB/M/CoCr dental crowns by adopting drag finishing (DF) technology. To evaluate the impact of this automatic post-processing, surface roughness measurements and geometrical investigations were undertaken. The microstructure was characterized using scanning electron microscopy (SEM), and the chemical composition was verified by energy-dispersive X-ray spectroscopy (EDAX). On outside surfaces, the DF post-processing decreased the initial surface roughness by 70–90%. The dental crown’s surface roughness value after DF post-processing was comparable to that of the basic form (cylinder). The lowest roughness was obtained with DF3 post-processing (Ra~0.60 μm). The inner surfaces were limitedly finished. The 3D surface texture showed that the DF method reduced the height of peaks, uniformizing the surfaces. CMM work compared the deviations between the virtual model and the printed samples before and after DF post-processing. This analysis revealed that dimensional deviations were reduced on the outside crown walls, ranging from +0.01 to +0.05 mm. The laser parameters and the heat treatment applied increased the hardness of CoCr crowns to 520 HV, but the proper DF conditions identified reduced the surface roughness and improved the accuracy. Full article
(This article belongs to the Special Issue Advances in Additive Manufacturing for Metallic Materials and Their Applications (3rd Edition))
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28 pages, 25525 KiB  
Review
Ultrasonic Vibration-Assisted Machining Particle-Reinforced Al-Based Metal Matrix Composites—A Review
by Xiaofen Liu, Yifeng Xiong and Qingwei Yang
Metals 2025, 15(5), 470; https://doi.org/10.3390/met15050470 - 22 Apr 2025
Viewed by 219
Abstract
Particle-reinforced Al-based matrix composites have great potential for application in aerospace, automotive manufacturing, and defense due to their high strength, hardness, and excellent wear and corrosion resistance. However, the presence of particles increases the processing difficulty, making it a typical difficult-to-machine material. In [...] Read more.
Particle-reinforced Al-based matrix composites have great potential for application in aerospace, automotive manufacturing, and defense due to their high strength, hardness, and excellent wear and corrosion resistance. However, the presence of particles increases the processing difficulty, making it a typical difficult-to-machine material. In recent years, ultrasonic vibration-assisted machining has been quite popular in manufacturing this kind of material. This paper reviews the research advancements in ultrasonic vibration-assisted machining of particle-reinforced Al-based matrix composites, providing a comprehensive analysis of the effects of introducing an ultrasonic energy field on tool wear, chip morphology, cutting force, cutting temperature, and surface integrity. Ultrasonic vibration periodically alters the contact state between the tool and the workpiece, effectively reducing the tool wear rate and extending the tool life. Meanwhile, ultrasonic vibration facilitates the fracture and ejection of chips, enhancing chip morphology and reducing energy consumption during the cutting process. Additionally, ultrasonic vibration significantly decreases cutting force and cutting temperature, contributing to the stability of the cutting process and improving processing efficiency. Regarding surface integrity, ultrasonic vibration-assisted machining refines the machined surface’s microstructure, reducing surface defects and residual stress, thereby significantly enhancing the machining quality. In the future, we will conduct in-depth research on the effects of ultrasonic energy on material properties in terms of softening effect, thermal effect, and stress superposition, further revealing the mechanism of ultrasonic vibration-assisted processing of particle-reinforced aluminum-based composite materials. Full article
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20 pages, 15332 KiB  
Article
Synergistic Effects of Thermal Cycles and Residual Stress on Microstructural Evolution and Mechanical Properties in Monel 400 and AISI 316L Weld Joints
by Balram Yelamasetti, Sri Phani Sushma, Zubairuddin Mohammed, Hussain Altammar, Mohammad Faseeulla Khan and Syed Quadir Moinuddin
Metals 2025, 15(5), 469; https://doi.org/10.3390/met15050469 - 22 Apr 2025
Viewed by 197
Abstract
The current study investigates the thermal, metallurgical, and mechanical results in similar and dissimilar weldments of Monel 400 and AISI 316L. Infrared thermography (IRT) was employed to record thermal cycles, while X-ray diffraction (XRD) was used to analyze the residual stresses post-welding. Mechanical [...] Read more.
The current study investigates the thermal, metallurgical, and mechanical results in similar and dissimilar weldments of Monel 400 and AISI 316L. Infrared thermography (IRT) was employed to record thermal cycles, while X-ray diffraction (XRD) was used to analyze the residual stresses post-welding. Mechanical properties were assessed through tensile and microhardness tests, and microstructural evolution was examined using energy-dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). IRT results showed peak temperatures of 1788 °C for Monel 400 and 1750 °C for AISI 316L. Residual stress analysis revealed compressive stresses of 293 MPa in dissimilar welds, compared to 235 MPa in Monel 400 and tensile stresses of 57 MPa in AISI 316L. Ultimate tensile strength (UTS) values were 543 MPa for dissimilar welds, 533 MPa for Monel 400, and 556 MPa for AISI 316L, with corresponding microhardness values of 207 HV, 203 HV, and 168 HV, respectively. Microstructural analysis identified coarse Ni-Cu phases in the Monel 400 heat-affected zone (HAZ), austenitic structures in AISI 316L, and intermetallic compounds in dissimilar welds. The findings highlight the impact of thermal distribution, residual stress, and microstructural evolution on weld performance, providing insights into optimized welding parameters for improved joint integrity and mechanical properties. Full article
(This article belongs to the Special Issue Advanced Metal Welding and Joining Technologies—2nd Edition)
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