Study Of Dispersion Behaviors Of TiC Nanoparticles In Molten Al Based On First Principles

The proposal of"Made in China 2025"and the implementation of sustainable development strategy have promoted the development of Al matrix composites.Especially,Al matrix TiC nanocomposites have excellent properties and are widely used in automotive,aerospace,electronic and optical instruments and other industries,which is a promising structural material.In recent years,a great deal of research has been done on the preparation of Al matrix TiC nanocomposites by agitation casting,but few studies have been carried out from the perspective of electronic structure.Besides,the self-dispersion of TiC nanoparticles in molten Al is still a long-term challenging problem.In addition,the coproducts（Al₃Ti and Al₄C₃）produced in the process will reduce the mechanical properties of the materials.In order to avoid experimental error and waste of resources,the first-principles method based on density functional theory can accurately predict the properties of materials,and explore the crystal structure,electronic structure and mechanical properties.In this paper,first-principles methods were employed to further explore the dispersion behaviors of TiC nanoparticles in molten Al at atomic and electronic scales.The effects of Al/TiC,Al（001）/Al₃Ti（001）and Al（111）/Al₄C₃（0001）interfaces on the mechanical properties of Al matrix TiC nanocomposites were analyzed.Firstly,the TiC nanoparticles were determined to be suitable as Al matrix reinforced particles by crystal structure optimization and bulk phase property analysis.Secondly,by calculating the adhesion work of the Al/TiC interfaces,it is determined that the bond strength of the-C interfaces is higher than that of the-Ti interfaces.It is found that the addition of impurity elements（such as Sr,Na etc.）reduces the adhesion of Al（110）/TiC（110）-C interface,which is an important reason for pseudo-dispersion of TiC nanoparticles in molten Al alloy.In addition,the adhesion work and Young’s equation are combined to confirm the good wettability of the-C interfaces.It is concluded that for the Al（100）/TiC（100）-C interface,when the Hamaker constants of Al was 266 z J,TiC nanoparticles with the radius of 20～79.30 nm could self-disperse in molten Al at 933K.Finally,tensile simulation,Griffith theory and differential charge density diagram were used to obtain the location of interface fracture,and it was verified that the uniform existence of Al/TiC interfaces in Al matrix are beneficial to the mechanical properties of materials,while the existence of Al（001）/Al₃Ti（001）and Al（111）/Al₄C₃（0001）interfaces are unfavorable.This paper provides an important reference and theoretical basis for the manufacture of Al matrix TiC nanocomposites.