Journal of Materials Engineering and Performance最新文献

This study aimed to investigate the synergistic effect of laser texturing and superhydrophobic coatings on lubrication and tribological properties. To this end, superhydrophobic Ni coatings with micro-nanocomposite structures were prepared on copper substrates using a laser etching-electrodeposition combination process. The frictional behavior of the superhydrophobic planar texture was examined in the context of dry grinding, depleted oil and rich oil conditions. Furthermore, the frictional behavior of the gradient texture was investigated at varying rotational speeds. The findings suggest that superhydrophobicity has a considerable impact on lubrication and friction reduction in the context of rich oil conditions. In comparison with oleophilic surfaces, the average coefficient of friction is reduced by approximately 20%. Furthermore, superhydrophobic surfaces can transition to mixed lubrication and dynamic pressure lubrication states more rapidly than hydrophilic surfaces when presented with gradient textures. In the case of composite textures, grooves can facilitate the delivery of lubricating fluid while simultaneously reducing the dynamic pressure of microfluidics and enhancing the bearing capacity of the oil film. Finally, the frictional lubrication mechanism of superhydrophobic surfaces under diverse operational conditions was meticulously delineated. This research offers valuable insights into the intricate relationship between surface texture and the underlying friction lubrication mechanism.

Hot-dip tin-lead alloy plating experiments were carried out on the surface of 45 steel. The effects of hot-dip plating temperature and time on the morphology of the coating and the interface diffusion layer were investigated. The experimental results show that increasing the temperature and time is beneficial to obtaining a good coating surface. The interface compound formed between the coating and the substrate is FeSn₂. With the increase in hot-dip plating time at 350 °C, the thickness of the coating and the diffusion layer generally shows an increasing trend, while the hardness of the coating shows a decreasing trend. In addition, molecular dynamics simulation was used to calculate the interface bonding energy of Sn-Pb/FeSn₂/45 steel with different FeSn₂ thicknesses at 350 °C. The simulation results indicate that with the increase in FeSn₂ thickness, the interface bonding energy of (45 steel+FeSn₂) is greater than that of (Sn-Pb+FeSn₂). The interface bonding energies of both (Sn-Pb+FeSn₂) and (45 steel+FeSn₂) first increase and then decrease.

The fabrication of multi-metallic materials, especially the combination of aluminum (Al) and copper (Cu), remains toward potential for applications requiring high performance with minimal weight. In this research, pluronic F-127 is used as a binder to build Al-Cu alloy via direct ink writing (DIW). In order to develop dense, load-bearing structures, the research intends to optimize rheological and post-processing parameters. The printability of different metallic inks with different solid volume fractions (30, 35, 40, and 45 vol.%) was examined. In order to evaluate nine test conditions (TCs), including varying the sintering temperature (500-900 °C), pressure (20-40 bar), and sintering time (1-3 h), a Taguchi experimental design was utilized. Mechanical and microstructural characterization was performed after the samples were printed and post-processed suitably. Rheology test depicts that the comparable viscosities, inks containing 35 vol.% Al and 45 vol.% Cu are appropriate for DIW. The maximum hardness value was obtained at TC9 (40 bar, 900 °C, 2 h), which is 22.31% greater than 40% Cu in Al alloy. Sintering temperature and pressure had a greater impact on porosity reduction than sintering time, according to microstructural research. This study determines the efficiency of DIW for fabricating dense, high-strength Al-Cu multi-metallic components and offers helpful recommendations for enhancing additive manufacturing's (AM) material formulation and processing parameters.

A pH-responsive protection coating capable of multiple repair cycles was fabricated by introduction of a functional silica microtubules (T-mSiO₂). Chitosan-polyethylene glycol polymer (CP), serving as a response switch, was grafted onto T-mSiO₂, with sodium phytate (PA) as the encapsulated inhibitor. FTIR, SEM, TG, and EDS tests confirmed the successful encapsulation of PA within T-mSiO₂ and the grafting of CP onto its surface. Upon coating damage, T-mSiO₂ releases PA in response to micro-pH changes, forming a protective film to achieve self-healing. Post-repair, CP re-covers T-mSiO₂ to prevent rapid PA depletion. By modifying the functional nanocontainer, the protective efficacy of the corrosion inhibitor was significantly enhanced, thereby prolonging the coating’s service life.

TiAl alloys are extensively utilized in aerospace and automotive applications, attributed to their superior properties. Nevertheless, attaining an optimal balance between strength and plasticity at elevated temperatures remains a significant challenge. This research successfully developed TiAl matrix composites strengthened by high-entropy alloys (HEAs) using powder metallurgy techniques. The present study probed the effects of particular high-entropy alloys, such as AlMnCrFeNi, CoMnCrFeNi, and CoMoCrFeNi, on the microstructural traits and high-temperature mechanical performance of composite materials. The findings indicated that incorporating HEA particles substantially boosts the sintering process of TiAl alloys, which in turn aids in creating dense composites. All three types of HEA particles were evenly dispersed within the TiAl matrix and exhibited excellent interfacial bonding with the matrix. Notably, numerous fine AlMnCrFeNi and CoMnCrFeNi particles generated in their corresponding composites. Moreover, the high-temperature tensile strength and ductility of all composites were improved relative to the pure TiAl alloy, due to fewer defects, finer grains, and synergistic deformation. Among these, the TiAl composites reinforced with CoMoCrFeNi exhibited the most pronounced enhancement in mechanical performance.

This paper investigated the ballistic impact behavior of high-strength bimodal Ti-5553 alloy armor against a 7.62 mm armor-piercing incendiary projectile. The V₅₀ limit velocity of the armor is high as 415 m/s, which is much higher than that of titanium alloy armors that are fabricated by coarse-grain Beta titanium alloy or bimodal Ti-6Al-4V titanium alloy. The penetration mechanism of the armor is the pure plugging, and the plugging leads to the formation of the thin adiabatic shear band (ASB) on the penetration channel of the armor. Compared with the initial bimodal microstructure consisting of the rodlike primary Alpha phase and the equiaxial prior Beta grain, the microstructure within the ASB evolves drastically. First, the rodlike primary Alpha phase transforms into Alpha fiber with the diameter of 200 nm. Second, with the intragranular Alpha (Alpha_Intra) → Beta transformation and the dynamic recrystallization of the transformed Beta phase, the equiaxial prior Beta grain disappears. Here, we attribute to excellent ballistic performance of the bimodal Ti-5553 to the higher dynamic strength, high critical strain for ASB formation, and microstructural evolution during failure/plugging along the ASB. In addition, the ultra-high dynamic strength of the armor could result in the blunting of the steel core during the penetration, which is also beneficial to the ballistic performance of the armor.

In this study, the CoCr_1.5NiTi_1.5Al_0.2 eutectic high-entropy alloys (EHEA, FCC + BCC), previously determined through thermophysical parameter calculations and phase diagram analysis, was selected to investigate suitable heat treatment process parameters. This study aims to optimize the alloy’s microstructure and mechanical properties while contributing foundational data to the heat treatment process library for EHEAs. The research findings revealed that heat treatment at temperatures of 700 °C and below led to the gradual coarsening of needle-like HCP-structured nano-precipitates within the eutectic phase, accompanied by an increase in the content of low-angle grain boundaries (LAGBs) in the alloy. Consequently, the compressive yield strength and fracture strength of the EHEA gradually increased, while the plastic strain progressively decreased. Starting from heat treatment at 900 °C, the CoCr_1.5NiTi_1.5Al_0.2 EHEA exhibited an increase in recrystallization content, a decrease in LAGB content, a reduction in dislocation density within the spherical FCC-structured nano-precipitates in the eutectic phase, and the dissolution and disappearance of needle-like HCP-structured nano-precipitates in the grain boundary regions. These changes ultimately resulted in a decrease in the alloy's compressive yield strength and fracture strength, along with an increase in plastic strain.

Zircaloy-2 is a zirconium-based alloy widely used in nuclear reactor components due to its excellent corrosion resistance, mechanical strength, and low neutron absorption. Its welding performance is critical for ensuring structural integrity in high-temperature environments. This study focuses on the welding of Zircaloy-2 pipes, optimizing process parameters to achieve high-quality joints. Fracture mechanics analysis was conducted to evaluate Mode I fracture strength (K_I) of both parent and weld specimens using single-edge notch tensile test, complemented by experimental and extended finite element method (XFEM) analysis. Results indicate that weld specimen exhibits a 31.8% higher K_I than parent specimen. The K_I of welded specimen is found to be 46.08 (text{MPa}sqrt{m})(experimentally) and 40.35 (text{MPa}sqrt{m}) (XFEM analysis). Around 16% increase in K_I is observed in weld specimen from parent specimen. A strong correlation was observed between experimental observation and numerical predictions, demonstrating the reliability of the adopted approach. These findings provide valuable insights for structural applications where Zircaloy-2 is extensively used in various industrial application.

SiC_f/SiC ceramic matrix composites are critical high-temperature structural materials for aerospace applications due to their exceptional thermomechanical properties. However, machining these composites generates significant quantities of micron-sized chips that migrate with cutting fluids into precision machine components, severely compromising their service life. This study investigates the tribological impact of SiC_f/SiC chips on GCr15 hardened steel (guideway material) by substituting chips with size distribution-matched SiC abrasive grains. Pin-on-disk wear tests were conducted to analyze the influence of abrasive size on friction coefficients and wear behavior. A single-abrasive wear model was developed using the Lagrangian finite element method, incorporating a modified Archard wear equation as a user-defined subroutine. The results indicate that increasing the abrasive particle size enhances the tribological response of SiCf/SiC composites, which is reflected in a higher coefficient of friction, greater wear volume and increased wear depth. This phenomenon is primarily because larger abrasive particles induce a stronger plowing effect and promote three-body wear, thereby shifting the material removal mechanism from mild wear to macroscopic brittle fracture. Furthermore, such particles significantly exacerbate damage features including plowing grooves and delamination. This work provides theoretical and technical foundations for protecting precision components in SiC_f/SiC ceramic matrix composites machining processes.

During the selective laser melting (SLM) process, the material undergoes rapid thermal cycles, resulting in significant residual stresses. Suitable process parameters are the key method to decrease these residual stresses. A thermo-mechanical model of AlSi10Mg alloy is established to investigate the effects of layer thickness, interlayer pause time, and laser spacing on residual stress during the SLM process. Studies have shown that components with thicker layers reduce temperature gradients, mitigating thermal stress accumulation. Longer interlayer pauses decrease cooling rates, enhancing heat diffusion and lowering residual stress. Laser spacing influences the heat-affected zone (HAZ); appropriate spacing ensures uniform HAZ distribution, reducing stress concentrations. Response surface analysis revealed that the interlayer pause time exhibited the least influence on residual stress, while the combined effect between layer thickness and interlayer pause time on the residual stress distribution is significant. The combination of parameters to minimize residual stress was predicted using the multi-objective approach as follows: a layer thickness of 0.05 mm, an interlayer pause time of 0.001 s, and a laser spacing of 0.137 mm. The application of optimized process parameters resulted in a reduction in residual stress from 63.9 to 54.6 MPa, corresponding to a 14.5% decrease in stress magnitude.