Journal of Materials Engineering and Performance最新文献

The development of efficient and stable transition metal-based electrocatalysts has always been an important step in the development of low-cost electrocatalysts for water splitting. High-entropy alloys (HEAs) comprising five or more elements in near-equiatomic proportions have attracted ever-increasing attention for their distinctive properties, such as exceptional strength, corrosion resistance, high hardness, and excellent ductility. Herein, FeCoCrNiAl, FeCoCrNiCu, and FeCoCrNiAlCu high-entropy alloys were prepared by vacuum arc furnace melting, and the effects of different element compositions on electrocatalytic reactions were explored. The results show that the FeCoCrNiAlCu high-entropy alloy (HEA) exhibits an excellent catalytic activity in a 0.5 M H₂SO₄ solution. Hence, the FeCoCrNiAlCu HEA exhibits an overpotential of 134 mV at 10 mA cm^-2 for the hydrogen evolution reaction (HER), which is lower than FeCoCrNiAl (189.3 mV), FeCoCrNiCu (191.3 mV) and the FeCoCrNiAlCu HEA possesses a relatively low Tafel slope (99.8 mV dec-1). Furthermore, it exhibits superior stability for i-t cycle. This work provides a useful method to design high-efficiency and low-cost high-entropy alloy catalysts for various necessary reactions.

Laser-directed energy deposition (L-DED) is a key additive manufacturing technology with extensive applications in aerospace, automotive, and biomedical industries due to its ability to fabricate complex geometries and repair high-value components. However, optimizing material strength, toughness, and process efficiency remains a critical challenge due to issues such as microstructural anisotropy, residual stress, and defect formation. This review presents a comprehensive multidimensional strategy for enhancing the performance of L-DED manufactured materials by integrating material selection, process control, structural optimization, and advanced manufacturing technologies. It evaluates the mechanical properties of commonly used materials and analyzes the influence of laser power, scanning strategies, and powder feed rate on melt pool behavior, grain morphology, and defects. Additionally, it explores novel structures and technological advancements aimed at improving microstructural uniformity and reducing porosity. The review also introduces an integrated optimization framework that combines AI-driven process control, real-time monitoring, and sustainable manufacturing techniques. By addressing these key challenges, this study contributes to the development of high-strength, defect-free, and industrially viable L-DED technologies, facilitating their broader adoption in high-performance engineering applications.

The present study investigated the effect of temperature and Cr addition on the slip-twinning competition in BCC-Fe through molecular dynamics simulations. A sharp crack {113}/(langle 110rangle) with a crack plane {113} and crack tip (langle 110rangle) was created. A tensile load with a strain rate of 10⁸ s^-1 was applied along the crack plane direction. Plastic deformation through twinning was noticed at two locations in the pure BCC-Fe system at T = 10 K, one at the crack tip and the other at the hard grip and the surface intersection region (surface region). A twinning to slip transition was noticed at T = 600 K at the crack tip due to the coupling of local stresses with thermal energy. However, the same transition was observed at a much higher temperature, 1000 K, in the surface region. A strong coupling between local stress concentration and thermal energy changed the deformation mode in BCC-Fe. Further, the effect of Cr on the deformation mode in BCC-Fe was studied at a fixed temperature of 10 K. Slip-stabilized twinning (slip followed by twin) was noticed at the crack tip and the surface region at 18 at.% Cr and 50 at.% Cr additions in BCC-Fe, respectively. Twinning to slip transition was noticed at the crack tip at 70 at.% Cr addition indicated the strong coupling between local and internal stresses. Further, twinning to slip transition in the entire Fe−70 at.% Cr binary alloy system was observed at 1300 K. Strong thermal energy, internal, and local stress coupling were noticed in the present study. The slip occurred through 1/2 (langle 111rangle) type edge dislocation nucleation.

NiTi alloys with varying La₂O₃ concentrations (0, 0.05, 0.10, and 0.15%) were fabricated using selective laser melting (SLM). The effects of La₂O₃ content on the microstructure, phase transformation behavior, and friction and wear properties of SLM-NiTi alloys were investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, microhardness testing, tensile testing, and friction and wear testing. The results show that the addition of La₂O₃ enhances the fluidity of the molten pool. Specifically, when the La₂O₃ content is 0.05%, the metallurgical bonding performance is optimal, the grains in the molten pool are more refined, and the microhardness value reaches a maximum value of 395.3 HV. With the increase of La₂O₃ content, the phase transformation temperature first increases and then decreases. It is worth noting that when the La₂O₃ content exceeds 0.10%, the reverse martensitic phase transformation is promoted. When the La₂O₃ content is 0.05%, the width and depth of the wear scar are the smallest, the amount of wear debris on the wear surface is reduced, and no obvious plastic deformation is observed, which indicates that both abrasive wear and adhesive wear effects are reduced, and there is only slight oxidation wear, thus showing the best wear resistance.

A series of problems, such as instability and sandwich shear failure, can quickly occur on brazed honeycomb aluminum panel, leading to difficulty during its processing and forming. Therefore, to obtain the best process parameters under different conditions, a combination of finite element simulation and experiment to study the compression performance of honeycomb aluminum panels at room temperature and high temperature was used in this project, which provides an effective technical way for compression of honeycomb aluminum panels. It was found that the outer stress of the honeycomb aluminum panel was more significant than the inner stress during flat pressing, and the strain value at the height of 1/3 after compression was about four times that of other positions. Through the flat compression experiment under different strain rates, it was found that with the decrease in strain rate, the maximum compressive stress that can be withheld increases, and the corresponding compression amount decreases. By studying the stress distribution on the flat side pressure at different temperatures, it was found that the rise in temperature leads to a more uniform stress distribution, which affects the final deformation.

Understanding the thermal response of materials with defects under microwave irradiation is critical for various applications, including electronics, materials science, and energy conversion. This study investigates microwave energy interaction with carbon defect-induced 3C-SiC by employing non-equilibrium molecular dynamics to gain insights into the molecular level heating of 3C-SiC in the presence of carbon defects. Simulation studies were conducted to explore the effects of microwave irradiation at varying electric field strengths and frequencies. The results demonstrated that introducing C-vacancies within the 3C-SiC system significantly improved microwave absorption, enabling the material to reach the melting point more rapidly than pure 3C-SiC. Moreover, this simulation study revealed that C-vacancies facilitated higher atomic diffusivity within the system. At 2.0% C-vacancy concentration, the 3C-SiC system exhibits 492, 260, and 77.8% higher diffusivity than 0.5, 1.5, and 1.5% C-vacancy concentration, respectively, at an electric field strength of 0.5 V/Å and frequency of 300 GHz. Pair correlation function study revealed a reduction in crystallinity by approximately 60 for 0.5% C-vacancy concentration during microwave irradiation. Pair correlation function analysis further confirmed that the accelerated solid-to-liquid phase transition occurred with increasing C-vacancy concentration and microwave exposure time.

This study investigated the impact of die bearing geometry on the surface cracking behavior, of a high strength AA6xxx alloy. Experimental and numerical methods were employed, along with differential scanning calorimetry tests to determine the material’s solidus temperature. Four different die geometries were employed in both the extrusion trial and the simulation. Extrusion trials were conducted for each die geometry over a range of extrusion speeds with the resulting surface defects being examined using SEM. The findings indicate that die bearing geometry significantly affects surface morphology and crack occurrence. Choked dies enabled crack-free extrusion at higher speeds, particularly a 12 mm choked bearing with a 1° angle, outperforming a 25 mm flat bearing and zero-bearing die. The 35 mm choked bearing achieved crack-free extrusion even at maximum extrusion speed, yielding smoother surfaces than the other dies. Numerical simulations demonstrated the differences in stress states using different die bearing geometries, showing that the choked bearings alter the stress state at the die corner to cause a transition from high tensile stress to lower tensile or compressive stress. The extrusion limit diagrams for different die bearings were also constructed based on the extrusion trial data to provide guidance for choosing appropriate extrusion parameters for future studies. This study adds a valuable contribution to the existing literature by shedding light on the role of die bearing geometry in controlling surface morphology and surface crack formation, providing important insights that can be used to optimize the extrusion process.

Fused Deposition Modeling (FDM) is a common additive manufacturing method used to produce intricate three-dimensional structures from thermoplastics. Its affordability and adaptability have contributed to its widespread use in fields such as medicine, electronics, and aerospace. This research focused on analyzing the mechanical properties of PLA (Polylactic Acid) samples produced via FDM. Since polymers display viscoelastic behavior above their glass transition temperature, this effect was disregarded due to the complexity of computations. Instead, key material properties, including Young’s modulus, thermal expansion, and conductivity, were considered temperature-dependent. To support the simulations, Differential Scanning Calorimetry (DSC) and Thermomechanical Analysis (TMA) were conducted to determine the PLA’s glass transition temperature and thermal expansion coefficients. Tensile tests were carried out at four different temperatures (25, 55, 85, and 115 °C), with results compared to finite element simulations in Abaqus. The findings showed that at 25 °C, PLA samples were rigid and glassy, but as they approached the glass transition temperature, they became softer and more rubber-like, leading to a significant reduction in tensile strength. The highest tensile strength was observed in the horizontally printed sample (H1) at 25 °C (31.66 MPa), while the lowest tensile strength was recorded in the vertically printed sample (V1) at 115 °C (3.41 MPa). All samples were fabricated using 100% infill density to ensure structural integrity and accurate comparison. The greatest elongation was measured at 55 °C. Experimental stress–strain curves closely matched simulation results, with an error margin of less than 5%. An analysis of distortion revealed that vertically printed samples deformed more due to layer accumulation, weaker interlayer adhesion, and extended cooling times. In contrast, horizontally printed samples experienced minimal distortion, benefiting from stronger platform contact and a lower number of layers.

In order to investigate the influence of the shape of the powder raw material on the coating properties, this paper investigates the plasma-sintered WC particles added to Fe-based powder to prepare coatings, and characterization methods such as coating microstructure, microhardness, and friction and wear are examined. The results show that with the increase of the mass fraction of added WC-17Co, the physical phases of the coatings appeared Fe₃W₃C₃ and Co₃W₃C₃, and at the same time, the microstructure of the coatings had a dense and homogeneous grain structure without obvious defects, and irregular aggregation of WC particles was clearly observed, and fine WC precipitates dispersed in the coatings were also observed. The hardness of the coating increases with the increase of WC-17Co content, and the spherical shape of the powder has a better improvement effect. With the addition of 30% WC-17Co, the hardness of the coating reaches 800HV0.2, which is 60% higher than that of the unadded coating. Spherical WC particles with 30% addition showed a more significant improvement, with a wear rate of 10-8, which was significantly better than that of non-spherical particles. Spherical particles have a smoother particle surface, which facilitates inter-particle movement and provides better spatial accumulation of powders, and at the same volume, the WC content of the spherical form of the powder is higher.

This study aims to precisely predict the onset of fracture during the single-point incremental forming (SPIF) of extra deep drawing (EDD) steel sheets using the Bao–Wierzbicki (BW) ductile damage model, incorporating anisotropy of the sheet metal in the analytical formulation. In this regard, a fresh attempt was made to optimize the theoretical BW fracture locus by optimizing the central hole (CH) fracture specimen geometry. Subsequently, four different CH specimens, namely CHD0, CHD2.5, CHD5, and CHD6, were considered by varying the hole-to-ligament width ratios within a range of 0-0.3. The CH specimen geometry was optimized by comparing the evolution of effective plastic strain with respect to stress triaxiality (left(eta right)) and the Lode angle parameter (left(theta right)). It was found that the CHD5 specimen experienced a purely uniaxial stress state with a (eta) and (theta) value almost equal to 0.33 and 1.0, respectively. Afterward, the BW damage model was calibrated using the four CH specimens, and different fracture loci were generated. Subsequently, the analytical fracture curves were validated with the safe and failed experimental strain data obtained through the SPIF of variable wall angle cone (VWAC) and variable wall angle pyramid (VWAP) cups. It was observed that the fracture locus obtained using CHD5 geometry accurately predicted the onset of fracture for SPIF cups. Further, the four distinct fracture loci were integrated separately into the finite element (FE) simulation of the SPIF process linked with the Hill48 anisotropic material model to estimate the formability. The error in dome height prediction was observed as 6.97% and 6.35% for VWAC and VWAP cups, respectively. It was concluded that the BW fracture locus calibrated using the CHD5 geometry was the optimized fracture locus. Furthermore, the surface strain distribution was predicted, incorporating the best-predicted BW fracture locus into the FE simulation. A decent agreement was observed between FE and experimental values.