Journal of Materials Engineering and Performance最新文献

This work investigated the co-effect of galvanic couple and alternating current (AC) on the corrosion behavior of FeCoNi HEA and X100 steel in simulated Golmud soil solution. The results indicate that the application of the two factors facilitates the corrosion of the HEA and steel, especially for X100 steel, reflected by increased corrosion rate and corrosion current density. Due to the alternation of positive and negative half-cycles of the applied AC, X100 steel acted as the anode of galvanic couple suffers strong dissolution and the γ-FeOOH/α-FeOOH proportion in the corrosion product film is remarkedly raised, increasing defective points within the film, which significantly decreases the anti-corrosion property of the steel. For the HEA, the combined effect of galvanic couple and AC interference disrupts the generation and stability of passive film, which diminishes the film protectiveness. Moreover, under the applied AC, the formation of soluble chlorides reacted between more adsorbed Cl^- ions and the oxides within passive film, promoting the film dissolution, which heightens the degree of corrosion pits on the HEA.

Hydrogen energy is considered an ideal choice for future energy due to its high energy density and environmental-friendliness. MOF-199 has attracted attention for its rich active sites and highly dispersed metal centers, but its poor conductivity limits its application in electrocatalysis. In this paper, MOF-199 was annealed to prepare C-MOF-Cu nanoparticles (NPs), which were then combined with the two-dimensional nanomaterial CuMoPd to ultimately form the C-MOF-Cu@CuMoPd catalyst. When the molar ratio of Cu:Mo:Pd was 18:2:5, the CuMoPd nanomaterial exhibited optimal electrocatalytic performance, requiring only a 118.0 mV overpotential to sustain a cathodic current density of 10 mA cm⁻², with a Tafel slope of 48.0 mV dec⁻¹. The framework structure of C-MOF-Cu NPs, derived from MOF-199, facilitated the uniform dispersion of CuMoPd nanomaterial, enhancing both the conductivity and surface area of the catalyst. This improvement further enhanced its electrocatalytic hydrogen evolution performance. At a loading of 20 wt.% CuMoPd, the overpotential and Tafel slope at a current density of 10 mA cm⁻² were 78.0 mV and 22.0 mV dec⁻¹, respectively, demonstrating the significant potential of C-MOF-Cu@CuMoPd in enhancing catalytic activity.

This study systematically investigated the stress–strain curves of a Mg-7Gd-3Y-1Zn-0.5Zr (VW73B) alloy within temperature and strain rate ranges of 440–500°C and 0.01–0.1s^-1, respectively. A strain-compensated constitutive model and three-dimensional (3D) hot processing maps were developed, combined with finite element simulation (FEM) to optimize the multidirectional forging (MDF) parameters. The reliability of both the constitutive models and the numerical simulations was further validated experimentally. The results demonstrate that the developed constitutive model accurately predicts the flow stress during hot deformation, with a mean relative error (MRE) of only 2.38%. The 3D processing maps reveal the progressive expansion of processable regions and the contraction of instability regions with increasing strain. The optimal working windows are identified as 460–480°C/0.01s^-1 under medium-strain conditions (ε = 0.4 ~ 0.6) and 450–490°C/0.1s^-1 under high-strain conditions (ε > 0.8). Finite element simulation indicates that increasing the MDF passes effectively enhances strain accumulation while reducing material anisotropy, with the coefficient of variation across all directions decreasing below 0.05 after 6 passes. MDF experiments confirmed that, under optimized parameters, the VW73B billet presented minor differences in average grain size and hardness values across three-dimensional surfaces, demonstrating superior formability and microstructural homogeneity.

This study investigates the mechanical properties and optimal process parameters to determine the single-objective performance characteristics of ytterbium fiber laser-welded Inconel 718, a nickel-based alloy, using the central composite design method. Inconel 718 (UNS N07718, W Nr 2.4668) is an austenitic nickel-based superalloy known for its excellent tensile strength and creep rupture properties. This superalloy plays a crucial role in aerospace turbine blades, particularly in critical rotating components. Modern aircraft also widely use it for aerofoils, supporting structures, and pressure vessels. Fiber laser welding is a well-established solid-state laser welding technique recognized for its narrow fusion zone, high intensity, and minimal thermal distortion. To optimize the input process parameters, including laser power (W), duty cycle (%), welding speed (mm/min), and frequency (Hz)—for the single-output response of ultimate tensile strength (MPa), the central composite design from response surface methodology (four factors at three levels) is employed. Analysis of variance (ANOVA) is used to identify the most influential process parameter. The weld zone exhibited high hardness across all experiments. An empirical relationship for ultimate tensile strength is established, and the optimized condition resulted in an ultimate tensile strength that is 4.7% higher than the base metal. Scanning electron microscope and x-ray diffraction tests show the details of the microstructure and the distribution of elements in the weld area.

The present study explored the development of hypereutectic Al-Si alloys such as Al-15Si (SF1), Al-15Si-0.5Ti (SF2), Al-15Si-1.0Ti (SF3), and Al-15Si-2Ti (SF4) alloys by spray forming, a technique that yields refined microstructures with minimal segregation, and examined the effects of titanium (Ti) on the microstructure and wear properties of alloys at various temperatures. Microstructural analysis revealed equiaxed aluminum (Al) matrices with distributed silicon (Si) phases and Al₃Ti intermetallics in Ti-containing alloys. The addition of Ti refined the microstructure and enhanced the refinement of Si particles. The hardness increased as Ti content increased in the alloy, with spray-formed alloys (SF) exhibiting 30-35% higher hardness than their as-cast (AC) counterparts at all temperatures. The SF alloys demonstrated improved wear resistance, with 50-65% lower wear rates than AC alloys at 25 °C and 68-82% lower at 250 °C. Specifically, the Al-15Si-2Ti SF alloy exhibited 62% and 82% lower wear rates than Al-15Si-2TiAC alloy at 25 °C and 250 °C, respectively. The coefficient of friction (COF) decreased with load for both AC and SF alloys, while COF values increased as the temperature increased. The AC alloys exhibited a 21-35% increase in coefficient of friction (µ) per unit rise in temperature, while SF alloys showed a significantly lower increase of 0.18-0.29%. The SF4 alloy demonstrated the lowest COF across the entire load and temperature range. Spray-formed hypereutectic Al-Si-Ti alloys demonstrate a high potential for aerospace and automotive applications due to their refined microstructure and enhanced wear resistance, achieved through addition of Ti, making them suitable for high-performing applications.

The fatigue strength of A6N01S-T5 aluminum alloy welded joints was studied by staircase test and scanning electron microscope fracture observation test. The results show that the conditional fatigue limit of double-pulse MIG welded joint is 97 MPa, which is higher than 92 MPa of single-pulse MIG welded joint. Fatigue fracture of double-pulse welded joints may occur in weld, fusion line, HAZ, or base metal zone. The fatigue fracture of single-pulse MIG welded joints mostly occurs in the weld zone. The pores were not found in the double-pulse MIG welded joints, which indicated that the double-pulse welding can avoid the fracture caused by pores.

This study investigates the effect of heat treatment on the microstructure and mechanical properties of a bimetallic structure composed of stainless steel 316L (SS316L) and maraging steel 1.2709 (MSteel 1.2709), fabricated using laser powder bed fusion (LPBF). The as-fabricated sample underwent two heat treatment processes: (i) stress relief at 600 °C (HT1) to reduce residual stresses and improve ductility, and (ii) solution treatment at 1000 °C (HT2) to enhance tensile strength and hardness. Microstructural analysis revealed grain refinement and reduced dislocation density in HT1, while HT2 led to homogenization and martensitic transformation in MSteel 1.2709. Tensile testing confirmed that HT2 resulted in the highest strength due to precipitation strengthening, whereas HT1 provided a balance between strength and ductility. These findings highlight the potential of optimized heat treatments to enhance the performance of LPBF-fabricated bimetallic structures for advanced engineering applications.

Heat-resistant Al alloys are urgently required at engineering applications. In this paper, the thermally stable microstructures and mechanical properties of a novel in situ hybrid (Al₃Ni + Al₂O₃)/Al composites synthesized via solid-state combustion of Al-(8%-15%)NiO system are investigated by annealing (200-600 °C), tensile tests at elevated temperature, and thermal expansion measurement. The results show that when the annealing temperature is lower than 500 °C, the morphology and size of Al₃Ni particles do not change significantly, while the merging and growing of Al₃Ni and Al₂O₃ particles are observed in 8-15%NiO-Al composites after annealing at 600 °C. The hardness retention rate of 12% and 15%NiO-Al composites reaches 90.7% and 90.3% after annealing at 500 °C for 100 h, respectively, which indicates that the composites have a good thermal stability below 500 °C. Tensile test at 350 °C indicates that the tensile strength of 15%NiO-Al composite can reach up to 113 MPa. The introduction of Al₃Ni and Al₂O₃ particles in Al matrix decreases the average CTE values. The excellent thermal stability of composites shows promising prospects at elevated temperature applications.

This study successfully fabricated the Fe₇₂Si₁₆B₇Cu₁Nb₄ iron-based amorphous alloy via melt-spinning and systematically investigated structural relaxation, magnetic domain structure evolution, and their impact on coercivity through precisely controlled multi-step annealing at primary annealing temperatures (510 , 520 , 530 , and 540 °C). The results reveal that as the annealing temperature increased from 510 °C to 540 °C, the volume fraction of the crystalline phase significantly increased from 59.53 to 71.43%, while the thickness of the residual amorphous layer decreased noticeably from 1.987 to 1.673 nm. Furthermore, the annealing treatment led to a substantial enhancement in the alloy’s saturation magnetic induction from 0.597 to 1.120 T, and a dramatic reduction in coercivity from 15.623 to 0.298 A/m. This research elucidates the critical role of enhanced atomic mobility, atomic rearrangement, and elimination of free volume in optimizing the magnetic domain structure and improving soft magnetic properties. This study provides valuable guidance for the design of high-sensitivity magnetic cores in power electronics, such as residual current protection devices, by optimizing coercivity through controlled annealing.