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16 pages, 4328 KiB  
Article
High-Throughput Study on Nanoindentation Deformation of Al-Mg-Si Alloys
by Tong Shen, Guanglong Xu, Fuwen Chen, Shuaishuai Zhu and Yuwen Cui
Materials 2025, 18(15), 3663; https://doi.org/10.3390/ma18153663 - 4 Aug 2025
Abstract
Al-Mg-Si (6XXX) series aluminum alloys are widely applied in aerospace and transportation industries. However, exploring how varying compositions affect alloy properties and deformation mechanisms is often time-consuming and labor-intensive due to the complexity of the multicomponent composition space and the diversity of processing [...] Read more.
Al-Mg-Si (6XXX) series aluminum alloys are widely applied in aerospace and transportation industries. However, exploring how varying compositions affect alloy properties and deformation mechanisms is often time-consuming and labor-intensive due to the complexity of the multicomponent composition space and the diversity of processing and heat treatments. This study, inspired by the Materials Genome Initiative, employs high-throughput experimentation—specifically the kinetic diffusion multiple (KDM) method—to systematically investigate how the pop-in effect, indentation size effect (ISE), and creep behavior vary with the composition of Al-Mg-Si alloys at room temperature. To this end, a 6016/Al-3Si/Al-1.2Mg/Al KDM material was designed and fabricated. After diffusion annealing at 530 °C for 72 h, two junction areas were formed with compositional and microstructural gradients extending over more than one thousand micrometers. Subsequent solution treatment (530 °C for 30 min) and artificial aging (185 °C for 20 min) were applied to simulate industrial processing conditions. Comprehensive characterization using electron probe microanalysis (EPMA), nanoindentation with continuous stiffness measurement (CSM), and nanoindentation creep tests across these gradient regions revealed key insights. The results show that increasing Mg and Si content progressively suppresses the pop-in effect. When the alloy composition exceeds 1.0 wt.%, the pop-in events are nearly eliminated due to strong interactions between solute atoms and mobile dislocations. In addition, adjustments in the ISE enabled rapid evaluation of the strengthening contributions from Mg and Si in the microscale compositional array, demonstrating that the optimum strengthening occurs when the Mg-to-Si atomic ratio is approximately 1 under a fixed total alloy content. Furthermore, analysis of the creep stress exponent and activation volume indicated that dislocation motion is the dominant creep mechanism. Overall, this enhanced KDM method proves to be an effective conceptual tool for accelerating the study of composition–deformation relationships in Al-Mg-Si alloys. Full article
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17 pages, 4153 KiB  
Article
Spherical Indentation Behavior of DD6 Single-Crystal Nickel-Based Superalloy via Crystal Plasticity Finite Element Simulation
by Xin Hao, Peng Zhang, Hao Xing, Mengchun You, Erqiang Liu, Xuegang Xing, Gesheng Xiao and Yongxi Tian
Materials 2025, 18(15), 3662; https://doi.org/10.3390/ma18153662 - 4 Aug 2025
Abstract
Nickel-based superalloys are widely utilized in critical hot-end components, such as aeroengine turbine blades, owing to their exceptional high-temperature strength, creep resistance, and oxidation resistance. During service, these components are frequently subjected to complex localized loading, leading to non-uniform plastic deformation and microstructure [...] Read more.
Nickel-based superalloys are widely utilized in critical hot-end components, such as aeroengine turbine blades, owing to their exceptional high-temperature strength, creep resistance, and oxidation resistance. During service, these components are frequently subjected to complex localized loading, leading to non-uniform plastic deformation and microstructure evolution within the material. Combining nanoindentation experiments with the crystal plasticity finite element method (CPFEM), this study systematically investigates the effects of loading rate and crystal orientation on the elastoplastic deformation of DD6 alloy under spherical indenter loading. The results indicate that the maximum indentation depth increases and hardness decreases with prolonged loading time, exhibiting a significant strain rate strengthening effect. The CPFEM model incorporating dislocation density effectively simulates the nonlinear characteristics of the nanoindentation process and elucidates the evolution of dislocation density and slip system strength with indentation depth. At low loading rates, both dislocation density and slip system strength increase with loading time. Significant differences in mechanical behavior are observed across different crystal orientations, which correspond to the extent of lattice rotation during texture evolution. For the [111] orientation, crystal rotation is concentrated and highly regular, while the [001] orientation shows uniform texture evolution. This demonstrates that anisotropy governs the deformation mechanism through differential slip system activation and texture evolution. Full article
(This article belongs to the Special Issue Nanoindentation in Materials: Fundamentals and Applications)
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20 pages, 51475 KiB  
Article
Mechanism-Driven Strength–Conductivity Synergy in Hypereutectic Al-Si Alloys Reinforced with Interface-Engineered Ni-Coated CNTs
by Xuexuan Yang, Yulong Ren, Peng Tang and Jun Tan
Materials 2025, 18(15), 3647; https://doi.org/10.3390/ma18153647 - 3 Aug 2025
Viewed by 104
Abstract
Secondary hypereutectic Al-Si alloys are attractive for sustainable manufacturing, yet their application is often limited by low strength and electrical conductivity due to impurity-induced microstructural defects. Achieving a balance between mechanical and conductive performance remains a significant challenge. In this work, nickel-coated carbon [...] Read more.
Secondary hypereutectic Al-Si alloys are attractive for sustainable manufacturing, yet their application is often limited by low strength and electrical conductivity due to impurity-induced microstructural defects. Achieving a balance between mechanical and conductive performance remains a significant challenge. In this work, nickel-coated carbon nanotubes (Ni-CNTs) were introduced into secondary Al-20Si alloys to tailor the microstructure and enhance properties through interfacial engineering. Composites containing 0 to 0.4 wt.% Ni-CNTs were fabricated by conventional casting and systematically characterized. The addition of 0.1 wt.% Ni-CNTs resulted in the best combination of properties, with a tensile strength of 170.13 MPa and electrical conductivity of 27.60% IACS. These improvements stem from refined α-Al dendrites, uniform eutectic Si distribution, and strong interfacial bonding. Strengthening was achieved through grain refinement, Orowan looping, dislocation generation from thermal mismatch, and the formation of reinforcing interfacial phases such as AlNi3C0.9 and Al4SiC4. At higher Ni-CNT contents, property degradation occurred due to agglomeration and phase coarsening. This study presents an effective and scalable strategy for achieving strength–conductivity synergy in secondary aluminum alloys via nanoscale interfacial design, offering guidance for the development of multifunctional lightweight materials. Full article
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21 pages, 3814 KiB  
Article
Features of the Structure of Layered Epoxy Composite Coatings Formed on a Metal-Ceramic-Coated Aluminum Base
by Volodymyr Korzhyk, Volodymyr Kopei, Petro Stukhliak, Olena Berdnikova, Olga Kushnarova, Oleg Kolisnichenko, Oleg Totosko, Danylo Stukhliak and Liubomyr Ropyak
Materials 2025, 18(15), 3620; https://doi.org/10.3390/ma18153620 - 1 Aug 2025
Viewed by 224
Abstract
Difficult, extreme operating conditions of parabolic antennas under precipitation and sub-zero temperatures require the creation of effective heating systems. The purpose of the research is to develop a multilayer coating containing two metal-ceramic layers, epoxy composite layers, carbon fabric, and an outer layer [...] Read more.
Difficult, extreme operating conditions of parabolic antennas under precipitation and sub-zero temperatures require the creation of effective heating systems. The purpose of the research is to develop a multilayer coating containing two metal-ceramic layers, epoxy composite layers, carbon fabric, and an outer layer of basalt fabric, which allows for effective heating of the antenna, and to study the properties of this coating. The multilayer coating was formed on an aluminum base that was subjected to abrasive jet processing. The first and second metal-ceramic layers, Al2O3 + 5% Al, which were applied by high-speed multi-chamber cumulative detonation spraying (CDS), respectively, provide maximum adhesion strength to the aluminum base and high adhesion strength to the third layer of the epoxy composite containing Al2O3. On this not-yet-polymerized layer of epoxy composite containing Al2O3, a layer of carbon fabric (impregnated with epoxy resin) was formed, which serves as a resistive heating element. On top of this carbon fabric, a layer of epoxy composite containing Cr2O3 and SiO2 was applied. Next, basalt fabric was applied to this still-not-yet-polymerized layer. Then, the resulting layered coating was compacted and dried. To study this multilayer coating, X-ray analysis, light and raster scanning microscopy, and transmission electron microscopy were used. The thickness of the coating layers and microhardness were measured on transverse microsections. The adhesion strength of the metal-ceramic coating layers to the aluminum base was determined by both bending testing and peeling using the adhesive method. It was established that CDS provides the formation of metal-ceramic layers with a maximum fraction of lamellae and a microhardness of 7900–10,520 MPa. In these metal-ceramic layers, a dispersed subgrain structure, a uniform distribution of nanoparticles, and a gradient-free level of dislocation density are observed. Such a structure prevents the formation of local concentrators of internal stresses, thereby increasing the level of dispersion and substructural strengthening of the metal-ceramic layers’ material. The formation of materials with a nanostructure increases their strength and crack resistance. The effectiveness of using aluminum, chromium, and silicon oxides as nanofillers in epoxy composite layers was demonstrated. The presence of structures near the surface of these nanofillers, which differ from the properties of the epoxy matrix in the coating, was established. Such zones, specifically the outer surface layers (OSL), significantly affect the properties of the epoxy composite. The results of industrial tests showed the high performance of the multilayer coating during antenna heating. Full article
(This article belongs to the Section Metals and Alloys)
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15 pages, 5148 KiB  
Article
Effect of Kr15+ Ion Irradiation on the Structure and Properties of PSZ Ceramics
by Madi Abilev, Almira Zhilkashinova, Leszek Łatka, Alexandr Pavlov, Igor Karpov, Leonid Fedorov and Sergey Gert
Ceramics 2025, 8(3), 95; https://doi.org/10.3390/ceramics8030095 (registering DOI) - 31 Jul 2025
Viewed by 129
Abstract
This article deals with the effect of Kr15+ ion irradiation on the structure and properties of partially stabilized zirconium dioxide (ZrO2 + 3 mol. % Y2O3) ceramics. Ion irradiation is used to simulate radiation damage typical of [...] Read more.
This article deals with the effect of Kr15+ ion irradiation on the structure and properties of partially stabilized zirconium dioxide (ZrO2 + 3 mol. % Y2O3) ceramics. Ion irradiation is used to simulate radiation damage typical of operating conditions in nuclear reactors and space technology. It is shown that with an increase in the irradiation fluence, point defects are formed, dislocations accumulate, and the crystal lattice parameters change. At high fluences (>1013 ions/cm2), a phase transition of the monoclinic (m-ZrO2) phase to the tetragonal (t-ZrO2) and cubic (c-ZrO2) modifications is observed, which is accompanied by a decrease in the crystallite size and an increase in internal stresses. Changes in the mechanical properties of the material were also observed: at moderate irradiation fluences, strengthening is observed due to the formation of dislocation structures, whereas at high fluences (>1014 ions/cm2), a decrease in strength and a potential amorphization of the structure begins. The change in the phase composition was confirmed by X-ray phase analysis and Raman spectroscopy. The results obtained allow a deeper understanding of the mechanisms of radiation-induced phase transformations in stabilized ZrO2 and can be used in the development of ceramic materials with increased radiation resistance. Full article
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20 pages, 4411 KiB  
Article
The Influence of the Defect Rate of Graphene on Its Reinforcing Capability Within High-Entropy Alloys
by Xianhe Zhang, Hongyun Wang, Chunpei Zhang, Cun Zhang and Xuyao Zhang
Nanomaterials 2025, 15(15), 1177; https://doi.org/10.3390/nano15151177 - 30 Jul 2025
Viewed by 153
Abstract
Graphene, a remarkable two-dimensional material, enhances the mechanical properties of high-entropy alloys as a reinforcing phase. This study investigated the influence of vacancy defects in graphene on the strengthening effect of FeNiCrCoCu high-entropy alloy through molecular dynamics simulations. The findings reveal that vacancy [...] Read more.
Graphene, a remarkable two-dimensional material, enhances the mechanical properties of high-entropy alloys as a reinforcing phase. This study investigated the influence of vacancy defects in graphene on the strengthening effect of FeNiCrCoCu high-entropy alloy through molecular dynamics simulations. The findings reveal that vacancy defects diminish graphene’s strength, resulting in its premature failure. In tensile tests, graphene with defects lowers the yield stress of the composite, yet it retains the ability to impede dislocations. Conversely, graphene exhibits a more pronounced strengthening effect during compression. Specifically, when the deletion of C atoms is less than 1%, the impact is negligible; between 1% and 6%, the strengthening effect diminishes; and when it surpasses 6%, the strengthening effect virtually ceases to exist. This research offers a theoretical foundation for optimizing graphene-reinforced composites. Full article
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17 pages, 7311 KiB  
Article
Fabrication of Cu-Al-Mn-Ti Shape Memory Alloys via Selective Laser Melting and Its Nano-Precipitation Strengthening
by Lijun He, Yan Li, Qing Su, Xiya Zhao and Zhenyu Jiang
Micromachines 2025, 16(8), 857; https://doi.org/10.3390/mi16080857 - 25 Jul 2025
Viewed by 228
Abstract
A Cu-11.85Al-3.2Mn-0.1Ti shape memory alloy (SMA) with excellent superelasticity and shape memory effect was successfully fabricated via selective laser melting (SLM). Increasing the energy density enhanced grain refinement, achieving a 90% refinement rate compared to cast alloy, with an average width of ~0.15 [...] Read more.
A Cu-11.85Al-3.2Mn-0.1Ti shape memory alloy (SMA) with excellent superelasticity and shape memory effect was successfully fabricated via selective laser melting (SLM). Increasing the energy density enhanced grain refinement, achieving a 90% refinement rate compared to cast alloy, with an average width of ~0.15 µm. Refined martensite lowered transformation temperatures and increased thermal hysteresis. Nanoscale Cu2TiAl phases precipitated densely within the matrix, forming a dual strengthening network combining precipitation hardening and dislocation hardening. This mechanism yielded a room-temperature tensile strength of 829.07 MPa, with 6.38% fracture strain. At 200 °C, strength increased to 883.68 MPa, with 12.26% strain. The maximum tensile strength represents a nearly 30% improvement on existing laser-melted quaternary Cu-based SMAs. Full article
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17 pages, 7494 KiB  
Article
The Effect of Strain Aging on the Microstructure and Mechanical Properties of Steel for Reel-Lay Coiled Steel Pipelines
by Yuxi Cao, Guofeng Zuo, Yang Peng, Lin Zhu, Shuai Tong, Shubiao Yin and Xinjun Sun
Materials 2025, 18(15), 3462; https://doi.org/10.3390/ma18153462 - 24 Jul 2025
Viewed by 351
Abstract
Deep-sea oil and gas pipelines undergo significant plastic strain during reel-lay installation. Additionally, the static strain aging phenomenon that occurs during service can further deteriorate the mechanical properties of the pipelines. This study investigates the plastic deformation mechanism of reel-lay pipeline steel by [...] Read more.
Deep-sea oil and gas pipelines undergo significant plastic strain during reel-lay installation. Additionally, the static strain aging phenomenon that occurs during service can further deteriorate the mechanical properties of the pipelines. This study investigates the plastic deformation mechanism of reel-lay pipeline steel by subjecting the test steel to 5% pre-strain followed by aging treatment at 250 °C for 1 h. The present study systematically correlates the evolution of mechanical properties with microstructural changes through microstructural characterization techniques such as EBSD, TEM, and XRD. The results demonstrate that after pre-straining, the yield strength of the experimental steel increases due to dislocation strengthening and residual stress generation, while its uniform elongation decreases. Although no significant changes in grain size are observed macroscopically, microstructural characterization reveals a substantial increase in dislocation density within the matrix, forming dislocation cells and walls. These substructures lead to a deterioration of the material’s work hardening capacity. Following aging treatment, the tested steel exhibits further increased yield strength and reduced uniform elongation. After aging treatment, although the dislocation density in the matrix slightly decreases and dislocation tangles are somewhat reduced, the Cottrell atmosphere pinning effect leads to a further decline in work hardening capability, ultimately resulting in the deterioration of plasticity in reel-lay pipeline steel. The instantaneous hardening exponent curve shows that the work hardening phenomenon becomes more pronounced in the tested steel after strain aging as the tempering temperature increases. Full article
(This article belongs to the Section Metals and Alloys)
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11 pages, 9979 KiB  
Article
The Microstructure Evolution of a Ni-Based Superalloy Turbine Blade at Elevated Temperature
by Xuyang Wang, Yanna Cui, Yang Zhou, Ze Li, Yuzhu Zhao and Jun Wang
Coatings 2025, 15(7), 835; https://doi.org/10.3390/coatings15070835 - 17 Jul 2025
Viewed by 285
Abstract
GTD 111 has been employed in first-stage blades in different gas turbines. The study of microstructural evolution is essential for the lifetime assessment and development of turbine blades. The microstructural stability of a 130 MW gas turbine first-stage blade at 800 °C was [...] Read more.
GTD 111 has been employed in first-stage blades in different gas turbines. The study of microstructural evolution is essential for the lifetime assessment and development of turbine blades. The microstructural stability of a 130 MW gas turbine first-stage blade at 800 °C was studied. The microstructure’s evolution was analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermodynamic calculation. As thermal exposure time increases, the shape of γ′ precipitates changes from square to spherical. During thermal exposure, MC particles formed and coarsened along the grain boundaries, and primary MC carbide decomposed into the η phase and M23C6. The stability of MC carbide at the grain boundaries was lower than that within the grains. MC carbide precipitated at the grain boundaries tends to grow along the boundaries and eventually forms elongated carbide. High-resolution transmission electron microscopy (HRTEM) images indicate that the orientation of the γ′ precipitate changes during the coarsening process. The GTD 111 alloy can be deformed through dislocation shearing at 800 °C. The hardness value initially increases, then decreases with further exposure, which is related to the reduced precipitation strengthening by γ′ precipitates and the reduction in the hardness of the γ matrix. Full article
(This article belongs to the Section Surface Characterization, Deposition and Modification)
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15 pages, 10188 KiB  
Article
The Effect of Aging Treatment on the Properties of Cold-Rolled Cu-Ni-Si-Co Alloys with Different Mg Contents
by Dan Wu, Jinming Hu, Qiang Hu, Lingkang Wu, Bo Guan, Siqi Zeng, Zhen Xing, Jiahao Wang, Jing Xu, Guojie Huang and Jin Liu
Materials 2025, 18(14), 3263; https://doi.org/10.3390/ma18143263 - 10 Jul 2025
Viewed by 352
Abstract
Cu-Ni-Si is a prominent example of a high-end lead frame copper alloy. The enhancement of strength without compromising electrical conductivity has emerged as a prominent research focus. The evolution of the precipitates exerts a significant influence on the strength and electrical conductivity of [...] Read more.
Cu-Ni-Si is a prominent example of a high-end lead frame copper alloy. The enhancement of strength without compromising electrical conductivity has emerged as a prominent research focus. The evolution of the precipitates exerts a significant influence on the strength and electrical conductivity of Cu-Ni-Si-Co-Mg alloys. In this paper, the effects of aging treatment and Mg addition on the properties and precipitates of cold-rolled Cu-Ni-Si-Co alloys were studied. The precipitate was (Ni, Co)2Si and was in a strip shape. During aging, precipitation and coarsening of the (Ni, Co)2Si precipitates were observed. In the early stage of aging, a significant number of fine (Ni, Co)2Si precipitates were formed. These fine precipitates could not only have a better effect of precipitation strengthening, but also impeded the dislocation movement, thus increasing the dislocation density and improving the dislocation strengthening effect. However, the coarsening of the precipitates became dominant with increasing aging times. Therefore, the strengthening effect was weakened. The addition of 0.12% Mg promoted finer and more diffuse precipitates, which not only improving the tensile strength by 100–200 MPa, but also exhibiting a smaller effect on the electrical conductivity. However, further increases in Mg contents resulted in a significant decrease in electrical conductivity, with little change in the tensile strength. The optimum amount of added Mg was 0.12%, and the aging parameters were 300 °C and 20 min. Full article
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20 pages, 13326 KiB  
Article
Stress–Strain and Structural Evolution on the Localized Interface of Stainless Steel Clad Plate
by Yinpeng Wang, Bo Gao, Qiqing Tian, Chunhui Jiang, Lu Zhu, Yanguang Cao, Wei Wei and Zhaodong Li
Materials 2025, 18(14), 3255; https://doi.org/10.3390/ma18143255 - 10 Jul 2025
Viewed by 328
Abstract
By applying different heat treatment processes (furnace cooling, air cooling, and water cooling), the stress–strain behavior of the localized interfacial region in weathering steel–stainless steel clad plates was investigated using nanoindentation, along with an analysis of interfacial microstructure formation and strengthening mechanisms. The [...] Read more.
By applying different heat treatment processes (furnace cooling, air cooling, and water cooling), the stress–strain behavior of the localized interfacial region in weathering steel–stainless steel clad plates was investigated using nanoindentation, along with an analysis of interfacial microstructure formation and strengthening mechanisms. The results show that samples in the as-rolled (R), furnace-cooled (FC), air-cooled (AC), and water-cooled (WC) conditions exhibit distinct interfacial morphologies and local mechanical properties. A well-defined interfacial layer forms between the base and cladding materials, where a high density of dislocations, grain boundaries, precipitates, and nanoscale oxides significantly enhances interfacial strength, resulting in a yield strength (Rp0.2) much higher than that of either adjacent metal. Across the transition from weathering steel to stainless steel, the interfacial region consists of ferrite—interfacial layer—“new austenite”—stainless steel austenite. Its formation is predominantly governed by element diffusion, which is strongly influenced by the applied heat treatment. Variations in diffusion behavior significantly affect the microstructural evolution of the dual-phase transition zone at the interface, thereby altering the local mechanical response. Full article
(This article belongs to the Section Metals and Alloys)
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26 pages, 8642 KiB  
Article
Ultra-High Strength and Specific Strength in Ti61Al16Cr10Nb8V5 Multi-Principal Element Alloy: Quasi-Static and Dynamic Deformation and Fracture Mechanisms
by Yang-Yu He, Zhao-Hui Zhang, Yi-Fan Liu, Yi-Chen Cheng, Xiao-Tong Jia, Qiang Wang, Jin-Zhao Zhou and Xing-Wang Cheng
Materials 2025, 18(14), 3245; https://doi.org/10.3390/ma18143245 - 10 Jul 2025
Viewed by 363
Abstract
This study investigates the deformation and fracture mechanisms of a Ti61Al16Cr10Nb8V5 multi-principal element alloy (Ti61V5 alloy) under quasi-static and dynamic compression. The alloy comprises an equiaxed BCC matrix (~35 μm) with uniformly dispersed nano-sized [...] Read more.
This study investigates the deformation and fracture mechanisms of a Ti61Al16Cr10Nb8V5 multi-principal element alloy (Ti61V5 alloy) under quasi-static and dynamic compression. The alloy comprises an equiaxed BCC matrix (~35 μm) with uniformly dispersed nano-sized B2 precipitates and a ~3.5% HCP phase along grain boundaries, exhibiting a density of 4.82 g/cm3, an ultimate tensile strength of 1260 MPa, 12.8% elongation, and a specific strength of 262 MPa·cm3/g. The Ti61V5 alloy exhibits a pronounced strain-rate-strengthening effect, with a strain rate sensitivity coefficient (m) of ~0.0088 at 0.001–10/s. Deformation activates abundant {011} and {112} slip bands in the BCC matrix, whose interactions generate jogs, dislocation dipoles, and loops, evolving into high-density forest dislocations and promoting screw-dominated mixed dislocations. The B2 phase strengthens the alloy via dislocation shearing, forming dislocation arrays, while the HCP phase enhances strength through a dislocation bypass mechanism. At higher strain rates (960–5020/s), m increases to ~0.0985. Besides {011} and {112}, the BCC matrix activates high-index slip planes {123}. Intensified slip band interactions generate dense jogs and forest dislocations, while planar dislocations combined with edge dislocation climb enable obstacle bypassing, increasing the fraction of edge-dominated mixed dislocations. The Ti61V5 alloy shows low sensitivity to adiabatic shear localization. Under forced shear, plastic-flow shear bands form first, followed by recrystallized shear bands formed through a rotational dynamic recrystallization mechanism. Microcracks initiate throughout the shear bands; during inward propagation, they may terminate upon encountering matrix microvoids or deflect and continue when linking with internal microcracks. Full article
(This article belongs to the Special Issue Fatigue, Damage and Fracture of Alloys)
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16 pages, 21960 KiB  
Article
Interplay of C Alloying, Temperature, and Microstructure in Governing Mechanical Behavior and Deformation Mechanisms of High-Manganese Steels
by Chenghao Zhang, Jinfu Zhao, Tengxiang Zhao, Ling Kong, Chunlei Zheng, Haokun Yang and Yuhui Wang
Metals 2025, 15(7), 779; https://doi.org/10.3390/met15070779 - 9 Jul 2025
Viewed by 208
Abstract
This study investigates the mechanical behavior and deformation mechanisms of Fe-30Mn-0.05C (30Mn0.05C) and Fe-34Mn-0.7C (34Mn0.7C) steels at room temperature (RT) and liquid nitrogen temperature (LNT). The 30Mn0.05C sample exhibited a significant enhancement in both strength and ductility at LNT, achieving a total elongation [...] Read more.
This study investigates the mechanical behavior and deformation mechanisms of Fe-30Mn-0.05C (30Mn0.05C) and Fe-34Mn-0.7C (34Mn0.7C) steels at room temperature (RT) and liquid nitrogen temperature (LNT). The 30Mn0.05C sample exhibited a significant enhancement in both strength and ductility at LNT, achieving a total elongation of 85%. In contrast, the 34Mn0.7C sample demonstrated superior ductility (90%) at RT, with a marginal reduction in plasticity but a remarkable increase in strength (>1100 MPa) at LNT. Compared to the 30Mn0.05C, the 34Mn0.7C, characterized by higher carbon content, displayed more pronounced dynamic strain aging (DSA) effects. Additionally, a greater density of deformation twins was activated at LNT, revealing a strong correlation between deformation twinning and DSA effects. This interplay accounts for the simultaneous strength improvement and ductility reduction observed in the 34Mn0.7C at LNT. Furthermore, the 34Mn0.7C sample exhibited a significantly refined grain structure after rolling, contributing to a substantial strength increase (approaching 1500 MPa) at the expense of ductility. This trade-off can be attributed to the pre-introduction of a higher density of dislocations and deformation twins during rolling, which facilitated strengthening but limited further plastic deformation. Full article
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20 pages, 13368 KiB  
Article
Influence of Soaking Duration in Deep Cryogenic and Heat Treatment on the Microstructure and Properties of Copper
by Dhandapani Chirenjeevi Narashimhan and Sanjivi Arul
J. Manuf. Mater. Process. 2025, 9(7), 233; https://doi.org/10.3390/jmmp9070233 - 7 Jul 2025
Viewed by 345
Abstract
The extensive use of copper in thermal and electrical systems calls for constant performance enhancement by means of innovative material treatments. The effects on the microstructural, mechanical, and electrical characteristics of copper in deep cryogenic treatment (DCT) and deep cryogenic treatment followed by [...] Read more.
The extensive use of copper in thermal and electrical systems calls for constant performance enhancement by means of innovative material treatments. The effects on the microstructural, mechanical, and electrical characteristics of copper in deep cryogenic treatment (DCT) and deep cryogenic treatment followed by heat treatment (DCT + HT) are investigated in this work. Copper samples were treated for various soaking durations ranging from 6 to 24 h. Mechanical properties such as tensile strength, hardness, and wear rate were analyzed. In the DCT-treated samples, tensile strength increased, reaching a peak of 343 MPa at 18 h, alongside increased hardness (128 HV) and a refined grain size of 9.58 µm, primarily due to elevated dislocation density and microstrain. At 18 h of soaking, DCT + HT resulted in improved structural stability, high hardness (149 HV), a fine grain size (7.42 µm), and the lowest wear rate (7.73 × 10−10 mm3/Nm), consistent with Hall–Petch strengthening. Electrical measurements revealed improved electron mobility (52.08 cm2/V·s) for samples soaked for 24 h in DCT + HT, attributed to increased crystallite size (39.9 nm), reduced lattice strain, and higher (111) texture intensity. SEM–EBSD analysis showed a substantial increase in low-angle grain boundaries (LAGBs) in DCT + HT-treated samples, correlating with enhanced electrical conductivity. Overall, an 18 h soaking duration was found to be optimal for both treatments. However, the strengthening mechanism in DCT + HT is influenced by grain boundary stabilization and thermal recovery and is different to DCT, which is strain-induced enhancement. Full article
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21 pages, 22021 KiB  
Article
Achieving High Strength in Mg-0.7Sm-0.3Zr Alloy via Room-Temperature Rotary Swaging: Radial Gradient Microstructure and Grain Refinement Mechanisms
by Jie Liu, Yuanxiao Dai, Zhongshan Li and Yaobo Hu
Materials 2025, 18(13), 3199; https://doi.org/10.3390/ma18133199 - 7 Jul 2025
Viewed by 375
Abstract
Room-temperature rotary swaging was conducted on microalloyed high-ductility Mg-0.7Sm-0.3Zr alloy rods to investigate microstructural and mechanical variations across different swaging passes and radial positions. The results indicate that following room-temperature rotary swaging, the alloy rods exhibit a large number of tensile twins and [...] Read more.
Room-temperature rotary swaging was conducted on microalloyed high-ductility Mg-0.7Sm-0.3Zr alloy rods to investigate microstructural and mechanical variations across different swaging passes and radial positions. The results indicate that following room-temperature rotary swaging, the alloy rods exhibit a large number of tensile twins and low-angle grain boundaries, leading to significant grain refinement. After two swaging passes, the microstructure exhibits a pronounced radial gradient, characterized by progressively finer grain sizes from the core to the edge regions, with a hardness difference of 3.8 HV between the edge and the core. After five swaging passes, the grain size was refined from an initial 4.37 μm to 2.02 μm. The yield strength and ultimate tensile strength of the alloy increased from 157 MPa and 210 MPa in the extruded state to 292 MPa and 302 MPa, respectively. This observed strengthening is primarily attributed to grain refinement, dislocation hardening, and texture strengthening, with grain refinement playing the dominant role. The grain refinement process during rotary swaging can be divided into two stages: in the initial stage, coarse grains are subdivided by tensile twinning; in the later stage, high-stress-induced grain boundary bulging leads to new dynamic recrystallization, further refining the microstructure. Full article
(This article belongs to the Section Metals and Alloys)
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