Xianhe Zhang

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.

High entropy alloys exhibit superior mechanical properties, especially wear resistance, making them crucial for wear-resistant and surface protection applications, necessitating in-depth research into their wear resistance and coating materials. This study utilizes molecular dynamics methods to perform a comprehensive investigation and meticulous analysis of the wear resistance of FeNiCrCoAl high entropy alloys, with the goal of providing crucial theoretical support for their practical applications. The FeNiCrCoAl high entropy alloy was applied as a coating onto an Al substrate, serving as the subject of friction simulations. By regulating the indentation depth of abrasive particles and coating thickness, we systematically examined how these factors affect the friction properties of the material. The findings reveal that when the depth of abrasive pressing is less than the coating thickness, the friction coefficient rises with increasing pressing depth; conversely, when the pressing depth exceeds the coating thickness, the friction coefficient decreases. As the coating thickness increases, the material generates a reduced proportion of disordered lattice structures during friction, accompanied by an increase in dislocation line density. This suggests a reduced wear from abrasive particles, indicating that thicker coatings enhance the material’s wear resistance.

Graphene, a remarkable two-dimensional material, enhances the mechanical properties of high entropy alloys as a reinforcing phase. This study uses molecular dynamics to explore the influence of vacant defects in graphene on mechanical properties of alloys. By incorporating graphene with varying vacancy defects into FeNiCrCoCu high entropy alloys containing initial dislocations, tensile and compressive simulations were conducted. Simulation results indicate that graphene, serving as the reinforcing phase in high-entropy alloy (FeNiCrCoCu), experiences a reduction in strength and load-bearing capacity due to its vacancy defects. These defects result in premature failure during the initial stages of strain and diminish the elastic strengthening effect. However, even with defects, graphene retains the ability to enhance the flow stress post-yield. A small number of defects can effectively impede dislocation motion, thereby strengthening the alloy. Conversely, an excessive number of defects allows dislocations to penetrate through the graphene, weakening the strengthening effect. Research has revealed that a defect structure characterized by a homogeneous loss of up to 5% of carbon atoms can enhance both the toughness of graphene and the yield strain of the alloy. Beyond this critical threshold, however, structural stability diminishes, leading to a significant reduction in the strengthening effect.

High entropy alloys have excellent wear resistance, so they have great application prospects in the fields of wear resistance and surface protection. In this study, the wear resistance of the FeNiCrCoCu high entropy alloy coating was systematically analyzed by the molecular dynamics method. FeNiCrCoCu high entropy alloy was used as a coating material to adhere to the surface of a Cu matrix. The friction and nanoindentation simulation of this coating material were carried out by controlling the ambient temperature. The influence of temperature on its friction properties was analyzed on five aspects: lattice structure, dislocation evolution, friction coefficient, hardness, and elastic modulus. The results show that with the increase of temperature, the disorder of the lattice structure increases, which leads to an increase of the tangential force and friction coefficient in the friction process. At 300 K and 600 K, the ordered lattice structure of the high entropy alloy coating material is basically the same, and thus its hardness is basically the same. However, the dislocation density at 600 K is significantly reduced compared with that at 300 K, resulting in an increase of the elastic modulus of the material from 173 GPa to 219 GPa. At temperatures of 900 K and 1200 K, lattice disorder takes place rapidly, and dislocation density also decreases significantly, resulting in a significant decrease in the hardness and elastic modulus of the material. When the temperature reaches 900 K, the wear resistance of the FeNiCrCoCu high entropy alloy coating decreases sharply. This work is of great value in the analysis of wear resistance of high entropy alloys at high temperature.

High entropy alloys have excellent wear resistance, so they have great application prospects in the fields of wear resistance and surface protection. In this study, the wear resistance of FeNiCrCoCu high entropy alloy coating was systematically analyzed by molecular dynamics method. FeNiCrCoCu high entropy alloy was used as a coating material to adhere to the surface of Cu matrix. The friction and nano indentation simulation of this coating material were carried out by controlling the ambient temperature. The influence of temperature on its friction properties was analyzed from five aspects: lattice structure, dislocation evolution, friction coefficient, hardness and elastic modulus. The results show that with the increase of temperature, the disorder of the lattice structure increases, which leads to the increase of the tangential force and the friction coefficient in the friction process. At 300K and 600K, the ordered lattice structure of the high entropy alloy coating material is basically the same, and thus their hardness is basically the same. However, the dislocation density at 600K is significantly reduced compared with that at 300K, resulting in the increase of the elastic modulus of the material from 173GPa to 219GPa. At the temperatures of 900K and 1200k, lattice disorder take place rapidly, and dislocation density also decreases significantly, resulting in a significant decrease in the hardness and elastic modulus of the material. When the temperature reaches 900K, the wear resistance of the FeNiCrCoCu high entropy alloy coating decreases sharply. This work is of great value to the analysis of wear resistance of high entropy alloy at high temperature.