Molecular Dynamics Simulation Of Interfacial Stability Of SiCp/Al Matrix Composites

Silicon carbide particle-reinforced aluminum(Si Cp/Al)matrix composites have excellent physicochemical properties such as high temperature resistance,wear resistance,corrosion resistance,high strength and stiffness,high thermal conductivity,adjustable coefficient of thermal expansion,etc.Meanwhile,their simple manufacturing process and low cost have great potential for applications in aerospace,advanced weapons,electronic packaging,etc.The stability of the interface between Si Cp/Al matrix composites,as a carrier connecting the reinforcement Si Cp to the matrix Al,is the key to the microscopic characteristics and macroscopic properties of the composites.In this paper,the structural evolution,bonding and wetting of Si Cp/Al matrix composites at the nanoscale are investigated by molecular dynamics simulations,and the effects of cooling rate,temperature,surface roughness topography and substrate groove width on the structural evolution and interfacial stability of the heterogeneous phase interface are investigated.The main research content includes:(1)The microstructures of Al-Al solid-liquid interface and Si Cp-Al solid-liquid interface at different cooling rates and holding times were studied by molecular dynamics methods,and the kinetic behavior and thermodynamic properties of these two interfaces were analyzed.For the Al-Al solid-liquid two-phase structure system,the smaller the cooling rate is,the easier it is to form a complete fcc phase structure with higher thermodynamic stability,and the phenomenon of sudden drop in potential energy is more obvious.For the C-terminated and Si-terminated interfacial structure systems of Si Cp-Al,during the insulation process,the atoms on both sides of the interface diffuse and penetrate into the vacuum layer,and the gap between the two surfaces gradually decreases and contacts each other until they are completely fused together,and the diffusion form shows surface diffusion;at the same cooling rate,the interfacial separation work of the solidified Si Cp/Al-C truncated system is greater than that of the Si Cp/Al-Si truncated system,which is similar to other calculated and experimental values.(2)Molecular dynamics method was used to study the changes of contact angles of Si Cp/Al smooth surface wetting structure system at different temperatures.For the Si Cp/Al smooth surface wetting structure system with different stacking methods and termination,the larger the interaction coefficient α and the higher the temperature,the smaller the contact angle between Al droplets and Si C substrate,which is close to the experimental results.With the increase of temperature,the interaction energy of the system showes a decreasing trend.For the Si Cp/Al-Cterminated and Si Cp/Al-Si-terminated systems with different stacking methods,the contact angles of Si Cp/Al-a-C and Si Cp/Al-a-Si systems are relatively smallest and the interaction energy is lowest at the same temperature,indicating better wettability and more stable systems.(3)Molecular dynamics method was used to study the changes of contact angle of Si Cp/Al rough surface wetting structure system at different temperatures,different rough surfaces and groove width.For the Si Cp/Al-C-terminated system fence and square-column rough surface,as the temperature increases,the contact angle of the system tends to decrease,the interaction between Al atoms in the system weakened,while the interaction between Al atoms and Si Cp became stronger,the bonding is tighter,the wettability is better,and the system is more stable.For the crater-shaped rough shaped surface of the Si Cp/Al-C-terminated system and the three different rough shaped surfaces of the Si Cp/Al-Si-terminated system,the change of wettability is not obvious with increasing temperature.For the Si Cp/Al-C-terminated fence-shaped rough surface system,the wettability of the system becomes better as the groove width increases.For the Si Cp/Al-C-terminated square column-shaped rough surface system,the contact angle of the system is larger overall with the increase of the groove spacing,and the variation of the contact angle is not obvious,and the wettability of the system is poor.For the Si Cp/Al-C-terminated crater-shaped rough surface system,the overall wettability of the system is better,and the variation of contact angle with temperature and groove width is not obvious.