Search Results (246)

The current research trends of production engineering are based on optimizing the machining process concerning human and environmental factors. High-performance materials, such as hardened steels, nickel-based alloys, fiber-reinforced polymer (FRP) composites, and titanium alloys, are classified as hard-to-cut due to their ability to maintain strength at high operating temperatures. Due to these characteristics, such materials are employed in applications such as aerospace, marine, energy generation, and structural. The purpose of this article is to investigate the machinability of these alloys under various cutting conditions. The purpose of this article is to compare cryogenic cooling and cryogenic processing from the perspective of machinability and sustainability in the manufacturing process. Compared to conventional machining, hybrid techniques, which mix cryogenic and minimal quantity lubricant, led to significantly reduced cutting forces of 40–50%, cutting temperatures and surface finishes by approximately 20–30% and more than 40%, respectively. A carbon footprint is determined by several factors including power consumption, energy requirements, and carbon dioxide emissions. As a result of the cryogenic technology, the energy consumption, power consumption, and CO₂ emissions were reduced by 40%, 28%, and 35%. Full article

This study examines the corrosion characteristics of GRX-810, a NiCoCr-based high entropy alloy, in a simulated marine environment represented by 3.5 wt.% NaCl solution. The research employs electrochemical and surface analysis techniques to evaluate the corrosion performance and protective mechanisms of this alloy. Electrochemical characterization was performed using potentiodynamic polarization to determine critical corrosion parameters, including corrosion potential and current density, along with electrochemical impedance spectroscopy to assess the stability and protective qualities of the oxide film. Surface analytical techniques provided detailed microstructural and compositional insights, with scanning electron microscopy revealing the morphology of corrosion products, energy-dispersive X-ray spectroscopy identifying elemental distribution in the passive layer, and X-ray diffraction confirming the chemical composition and crystalline structure of surface oxide. The results demonstrated distinct corrosion resistance behavior between the different processing conditions of the alloy. The laser powder bed fused (LPBF) specimens in the as-built condition exhibited superior corrosion resistance compared to their hot isostatically pressed (HIPed) counterparts, as evidenced by higher corrosion potentials and lower current densities. Microscopic examination revealed the formation of a dense, continuous layer of corrosion products on the alloy surface, indicating effective barrier protection against chloride ion penetration. A compositional analysis of all samples identified oxide film enriched with chromium, nickel, cobalt, aluminum, titanium, and silicon. XRD characterization confirmed the presence of chromium oxide (Cr₂O₃) as the primary protective phase, with additional oxides contributing to the stability of the film. This oxide mixture demonstrated the alloy’s ability to maintain passivity and effective repassivation following film breakdown. Full article

In this study, a TiNi alloy with a composition of 50 at.% of titanium and 50 at.% of nickel is investigated in terms of its corrosion and biocompatibility behavior for biomedical applications. The corrosion measurements, which include the determination of open-circuit potential and linear polarization resistance measurements, cyclic polarization measurements, and electrochemical impedance spectroscopy in 9 g L⁻¹ NaCl, show that TiNi has satisfactory corrosion stability. According to the SEM and EDS analysis, after cyclic polarization, pitting corrosion occurred, accompanied by the dissolution of the unstable Ti₂Ni inclusions. The analysis also showed that TiNi has good biocompatibility for human osteoblast-like cells, as determined by the mitochondrial activity, which was assessed using a direct contact test following ISO standard 10993-5, via scanning electron microscopy (SEM) and fluorescent microscopy. Full article

Reducing structural mass and volume is critical to improving efficiency and payload capacity in next-generation small satellites and CubeSats. Additive manufacturing, particularly material extrusion, offers design flexibility and enables the production of lightweight, functional metallic components. This study investigates the integration of nickel–titanium shape memory alloy wires into aluminum-based matrices using a sinter-based material extrusion process, aiming to develop compact actuator systems for aerospace applications. A customized AlSi7Mg aluminum alloy feedstock was extruded into filament form, printed, and embedded with shape memory alloy wires, allowing consolidation during sintering. X-ray micro-computed tomography was used to analyze internal defects and matrix–wire interfacial contact, before and after sintering. Tensile testing of the embedded actuator structures revealed effective mechanical bonding and actuation behavior. The results demonstrate that controlled shrinkage and interfacial bonding enable reliable embedding of shape memory elements without compromising structural integrity. This work provides a promising framework for developing multifunctional aerospace components, where active actuation and structural efficiency can be combined through advanced material extrusion-based manufacturing. Full article

This study investigates the microstructure and mechanical properties of Inconel 718, a nickel-based alloy, reinforced with ceramic phases via additive manufacturing. Two reinforcement strategies were explored: in situ formation of ceramic phases through titanium powder addition, and direct incorporation of Cr₂O₃ and TiO₂ ceramic particles. Both approaches significantly modified the alloy’s microstructure and elemental distribution. The in situ formation method produced leaf-like Ti-rich precipitates (up to 70.13 wt%), while direct ceramic addition suppressed the preferred orientation of the Laves phase and promoted the formation of NbC precipitates. Microhardness increased by 19.4% with titanium addition, compared to a modest 1.3% improvement with direct ceramic addition. Tensile testing revealed that titanium powder enhanced ultimate tensile strength but reduced elongation, whereas direct ceramic addition led to decreases in both strength and ductility. Wear resistance evaluation showed that direct ceramic addition yielded superior performance, evidenced by the lowest friction coefficient (0.514) and smallest wear volume (16,290,782 μm³). These findings demonstrate the effectiveness of ceramic reinforcement strategies in optimizing the mechanical and tribological behavior of additively manufactured Inconel 718, and offer valuable guidance for the development of wear-resistant components such as those used in hydraulic support systems. Full article

Fluoride mouthwashes are often recommended by dental professionals due to their proven benefits for oral hygiene. However, it is vital to acknowledge that these products may have undesirable effects on orthodontic treatment outcomes, particularly by altering the biomechanical properties of orthodontic devices and their components. To gain a comprehensive understanding of this potential issue, an extensive and systematic search was conducted across seven distinct databases. PRISMA extension for scoping reviews (PRISMA ScR) guidelines were followed. Following a detailed evaluation and careful scrutiny of the available evidence, a total of seven relevant studies met the inclusion criteria and were incorporated into the current scoping review. Findings indicated that regular intraoral use of fluoride-containing mouthwashes could lead to heightened corrosion and greater release of metal ions from stainless-steel brackets and nickel–titanium (NiTi) archwires. Additionally, the mechanical properties and structural integrity of titanium–molybdenum alloy (TMA) wires were negatively influenced by exposure to fluoride mouthwashes. Although existing evidence highlights these potential drawbacks, there remains a clear necessity for additional comprehensive research. Given the possibility that fluoride mouthwashes could adversely influence orthodontic treatment effectiveness, orthodontists and dental clinicians must exercise cautious judgment and deliberate consideration when prescribing fluoride-based mouthwashes for patients undergoing orthodontic therapy. Full article

This study investigates the effects of aluminum (Al) and titanium (Ti) additions on the porosity, microstructure, and corrosion performance of Hastelloy C276-based coatings fabricated via laser cladding on nodular cast iron substrates. Nickel-based alloy powders blended with varying Ti (1–10 wt.%) and Al (0.5–2.5 wt.%) contents were deposited under optimized laser parameters. Microstructural characterization revealed that Ti addition refined the grain structure and promoted the formation of TiC phases, while Al addition dispersed eutectic networks into isolated island-like structures. Both elements effectively suppressed porosity by reducing gas entrapment during solidification. However, excessive Ti (10 wt.%) induced brittle fracture due to TiC agglomeration, and Al addition caused interfacial cracks owing to Al₂O₃ formation. Electrochemical tests in a 3.5 wt.% NaCl solution indicated that Al/Ti additions enhanced initial passivation but reduced corrosion resistance due to weakened oxide film stability. XPS analysis revealed that Al-enriched coatings formed Al₂O₃ and Al(OH)₃, whereas Ti-modified coatings developed TiO₂ and TiC, both influencing the passivation behavior. These findings provide critical insights into tailoring laser-clad coatings for marine applications by balancing porosity suppression and corrosion resistance. Full article

The miniaturization of smart materials has become a new trend in the modern manufacturing industry due to its enormous application in the aerospace, biomedical, and automobile sectors. Nickel–titanium (NiTi)-based binary shape memory alloys (SMAs) are one of the smart materials with certain supreme features like shape memory effect, pseudo-elasticity, high ductility, strong corrosion-resistance, and elevated wear resistance. For this, several micro-machining processes have been developed to machine NiTi SMAs. This paper summarizes all of the conventional and non-conventional micro-machining processes employed to machine NiTi SMAs. In this review process, the surface integrity, dimensional accuracy of the machined surface, cutting force and tool wear analysis during conventional and non-conventional micro-machining of NiTi SMA are evaluated mostly with the aid of input process variables like cutting speed, depth of cut, width of cut, types of coolants, tool coating, discharge voltage, capacitance, laser fluence, pulse duration, scan speed, electrolysis concentration and gap voltage. The optimization of process parameters using different methods during conventional and non-conventional micro-machining of NiTi SMAs is also analyzed. The problems faced during conventional micro-machining of NiTi SMAs are overcome by non-conventional micro-machining processes as discussed. The present study aims to recognize potential developments in the improvement of the micro-machinability of NiTi SMAs. Full article

The great capability of additive manufacturing to produce parts with complex, even impossible to achieve, geometries through five-or-more-axis machining or other conventional processes opened a promising future decades ago. For its part, mature subtractive manufacturing presents problems of material waste, especially relevant in the case of superalloys used in fields such as aerospace. From the need to overcome the limitations of both and take advantage of their capabilities, the new paradigm of hybrid additive and subtractive manufacturing was born, which today is defined as a hybrid flow of subprocesses that interact with the part in the same machine. This paper presents a review of the emerging trends in additive–subtractive manufacturing over the last five years. This review has been carried out by applying an adaptation of the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) methodology to the field of manufacturing engineering. Specifically, open access papers published in English between 2020 and 2024, collected in prestigious journals (classified as Q1 and Q2 within the ranking of their respective categories according to the Journal Citation Report), and peer-reviewed conference proceedings of recognized prestige have been selected. From the analysis of the selected articles, it is concluded that hybrid additive and subtractive manufacturing is especially focused on the aerospace field, using titanium and nickel alloys, combining processes among which DED (directed energy deposition) and milling stand out. Full article

Refractory metal-based Mo-Si-B alloys have long been considered the most promising candidates for replacing nickel-based superalloys in the aerospace and energy sector due to their outstanding mechanical properties and good oxidation of the Mo-silicide phases. In general, the addition of vanadium to Mo-Si-B alloys leads to a significant density reduction, while small amounts of titanium provide additional strengthening without changing the phase evolution within the Mo_ss-Mo₃Si-Mo₅SiB₂ phase field. In this work, high-energy ball milling studies on Mo-40V-9Si-8B, substituting both molybdenum and vanadium with 2 and 5 at. % Ti in all constituents, were performed to evaluate the potential milling parameters and investigate the effects of Ti doping on the milling characteristics and phase formation of these multicomponent alloys. After different milling durations, the powders were analysed with regard to their microstructure, particle size, oxygen concentration and microhardness. After heat treatment, the silicide phases (Mo,V)₃Si and (Mo,V)₅SiB₂ precipitated homogeneously within a (Mo,V) solid solution matrix phase. Thermodynamic phase calculations using the CALPHAD method showed good agreement with the experimental phase compositions after annealing, confirming the stability of the observed microstructure. Full article

A novel parameter optimization method for additively manufacturing nickel–titanium (NiTi) alloys using laser powder bed fusion (LBPF) was developed. Compared with the conventional NiTi alloy and the previously reported LPBF-NiTi alloy, the LBPF-NiTi alloy prepared with these parameters exhibits excellent tensile properties and an anisotropic microstructure. Since distinct regions of orthopedic implants have specific functional requirements, we investigated the anisotropy of this LPBF-NiTi in terms of its osteoinductive capacity to determine the appropriate building direction for prosthesis fabrication. The biosafety of the transverse (XY-NiTi) and longitudinal (XZ-NiTi) planes was assessed through cytotoxicity assays. Comparative analyses of the biological activities of these planes were conducted by evaluating the adherent cell counts, the adhesion morphology, and the expression of osteogenic-related genes and factors in adherent cells. Compared with XZ-NiTi, XY-NiTi exhibited superior cell adhesion properties. Additionally, the expression levels of osteogenic markers (RUNX2, ALP, OPG, and OCN) were significantly greater in bone marrow mesenchymal cells (BMMCs) adhered to XY-NiTi than in those adhered to XZ-NiTi. These results indicate a greater osteogenic potential in the XY-NiTi group. XY-NiTi was more advantageous as an implant–bone contact surface. Building implant products in the direction perpendicular to the load-bearing axis enhances biofixation; thus, this is the preferred orientation for manufacturing orthopedic implants. Full article

In the context of Al-Kharj city, which is steadily advancing as an industrial and manufacturing hub within Saudi Arabia, this study has significant relevance. The city’s focus on metal forming, fabrication, and materials engineering makes it crucial to optimize processes such as hot deformation of metallic alloys for various sectors, including aerospace, automotive, oil and gas, and structural applications. By assessing and comparing phenomenological and physical material models for nickel, aluminum, titanium, and iron-based alloys, this study aids Al-Kharj industries in advancing their process simulation and predictive performance. Thus, this study aims to evaluate the proposed phenomenological and physically based constitutive models for Ni-, Al-, Ti-, and Fe-based alloys to enhance the accuracy of high-temperature deformation simulations. Phenomenological models investigated include the Johnson–Cook (JC), Fields and Backofen (FB), and Khan–Huang–Liang (KHL) formulations, while the Zerilli–Armstrong (ZA) model represents the physical category. Additionally, various modifications to these models are explored. Model parameters are calibrated using the Levenberg–Marquardt algorithm to minimize mean square error. Performance is assessed through key statistical metrics, including the correlation coefficient (R), average absolute relative error (AARE), and root mean square error (RMSE). Of the 32 models analyzed, a modified version of the JC model delivers the highest accuracy across all alloys. Furthermore, four other modifications, one each for the JC and ZA models and two for the FB model, exhibit superior predictive capability for specific alloys. This makes this study valuable not just academically, but also as a practical resource to boost Al-Kharj’s industrial competitiveness and innovation capacity. Full article

Three alloys differing in their nominal chemical composition (Ni₅₀Ti₅₀, Ni₅₁Ti₄₉, and Ni₅₂Ti₄₈) were produced in the form of powders using high-energy ball milling. Their microstructure, morphology, structure, and phase composition were studied using the X-ray diffraction technique, scanning, and transmission electron microscopy. For the detailed structural analysis, the Rietveld method was used. The results show that each of the alloys consists of three fractions: fine, medium, and thick. The fractions varied in particle/agglomerate size from 200 nm to 800 μm. Additionally, they varied in phase composition. The fine fraction comprised a mixture of amorphous and nanocrystalline phases. Additionally, the medium and coarse phases showed crystalline solid solutions formed on the bases of nickel or titanium, as well as a crystalline bcc phase—a precursor of the parent phase (B2). The largest contribution in the alloy powders, over 80%, comes from the amorphous–nanocrystalline mixture (ANM). The increase in the nickel content resulted in an increase in ANM quantity of 3 wt.%. Similarly, the weight content of the titanium-based solid solution increased to about 7 wt.%. In contrast, the quantity of the nickel-based solid solution decreased from 3 wt.% to approximately 1 wt.% in the Ni₅₀Ti₅₀ and Ni₅₂Ti₄₈ alloys. Full article

Hip joint implants are among the most prevalent types of medical implants utilized for the replacement of damaged joints. The utilization of modern implant materials, such as cobalt–chromium alloys, stainless steel, titanium, and other titanium alloys, is accompanied by challenges, including the toxicity of certain elements (e.g., aluminum, vanadium, nickel) and excessive Young’s modulus, which adversely impact biomechanical compatibility. A mismatch between the stiffness of the implant material and the bone tissue, known as stress shielding, can lead to adverse outcomes such as bone resorption and implant loosening. Recent studies have shifted the focus to β-titanium alloys due to their exceptional biocompatibility, corrosion resistance, and low Young’s modulus, which is close to the Young’s modulus of bone tissue (10–30 GPa). In this study, the microstructure, mechanical properties, and phase stability of the Ti-38Zr-11Nb alloy were investigated. Energy dispersion spectrometry was employed to confirm the homogeneous distribution of Ti, Zr, and Nb in the alloy. A subsequent microstructural analysis revealed the presence of elongated β-grains subsequent to rolling and quenching. Furthermore, grinding contributed to the process of recrystallization and the formation of subgrains. X-ray diffraction analysis confirmed the presence of a stable β-phase under any heat treatment conditions, which can be explained by the use of Nb as a β-stabilizer and Zr as a neutral element with a weak β-stabilizing effect in the presence of other β-stabilizers. Furthermore, the modulus of elasticity, as determined by tensile testing, exhibited a decline from 85 GPa to 81 GPa after annealing. Mechanical tests demonstrated a substantial enhancement in tensile strength (from 529 MPa to 628 MPa) concurrent with a 32% reduction in elongation to fracture of the samples. These alterations are attributed to microstructural transformations, including the formation of subgrains and the rearrangement of dislocations. This study’s findings suggest that the Ti-38Zr-11Nb alloy has potential as a material of choice due to its lower Young’s modulus compared to traditional materials and its stable β-phase, which enhances the implant’s durability and reduces the risk of brittle phases forming over time. This study demonstrates that the corrosion resistance of titanium grade 2 and Ti-38Zr-11Nb is comparable. The material in question exhibited no evidence of cytotoxic activity in the context of mammalian cells. Full article

This work presents an integrated directed energy deposition (DED) approach utilizing a multi-powder feeder with real-time continuously variable composition functionality, a multi-powder mixer and a multi-powder nozzle to fabricate Ti-Ni-Nb gradient alloys with controlled compositional variations. The high-throughput methodology enables rapid alloy design and optimization by allowing precise manipulation of chemical composition and phase structures within a single deposited track. The EDS analysis confirms a gradual increase in titanium content, a nearly constant nickel content and a decrease in niobium along the scanning path, aligning with the expected powder-feeding trends. X-ray diffraction (XRD) analysis further reveals a phase transition from niobium-rich intermetallic compounds (NbNi₄, Nb₈Ni) at the beginning of the deposition to titanium-rich phases (Ti, Ti₂Ni) at the end, demonstrating the ability to tailor phase distributions through real-time composition control. This high-throughput methodology enables rapid alloy design and optimization by integrating theoretical predictions with experimental phase screening. This study establishes a novel framework for the rapid discovery and optimization of functionally graded materials, paving the way for advanced applications in aerospace, biomedical implants and high-performance structural components. Full article