The First-principles Calculations Of Zirconium-Aluminum Alloy System

Due to its excellent physical and chemical performance,Zirconium（Zr）and its alloys have been widely used in various fields.The mature Zr alloy systems currently studied are Zr-Sn and Zr-Nb,but relatively few studies on Zr-Al.Therefore,systematic and in-depth research on the Zr-Al system using theoretical calculation methods can not only provide theoretical support for the corresponding experimental results,but also lay a theoretical foundation for the development and design of subsequent materials.In this paper,the first-principles calculation method based on density functional theory was used to carry out research on atomic diffusion,two-phase interface and generalized stacking fault energy of the Zr-Al alloys.The specific research content is as follows:The possible migration paths of Zr and Al atoms in Zr ₃Al were analyzed,and the migration energy barriers of each migration path were calculated.From the perspective of diffusion activation energy,the most feasible diffusion mechanism of Zr and Al atoms in Zr₃Al are the nearest neighbor diffusion mechanism induced by V _Zr and the anti-site assist mechanism,respectively.In addition,the effects of Hf,Nb,Sc and Ti on the self-diffusion mechanism of Zr₃Al were explored,and we found that the key factor affecting the self-diffusion of Zr₃Al is the radius of the solute atoms.The migration energy barriers of Al and Zr atoms mediated by V_Al at the interface of pure Al/Al₃Zr and alloyed by Nb,Ti,Cu and Sc were calculated.The result show that the atomic diffusion is significantly inhibited due to the introduction of alloying elements,then the Al₃Zr phase transition process become difficult.We considered the synergistic effects of vacancy and alloying elements on interfacial bonding strength,it is found that the alloying effect of Nb is the best at interfaces with and without the V_Al,respectively,while the Cu is relatively poor,which may due to the difference in the degree of electron localization of the Al atoms near different alloying elements.The generalized stacking fault energy curves of Al-X（X=Sc,Ti,V,Nb,Mo,Hf,Ta,W）before and after the introduction of Zr were calculated and plotted,the result show that due to the introduction of Zr,not only the intrinsic stacking fault energies of each system are reduced,but also the stacking fault energy reach the theoretical limitation value in the concentration range of solute content at 0.1%-0.2%.Meanwhile,the material can maintain a good stability of stacking fault energy in a large temperature range.In addition,the introduction of Zr have the greatest influences on the twinning tendency of Al-Sc and Al-Hf,which theoretically significantly improves the plastic deformation ability of the material.