Microstructure Mechanism Study Of Irradiation Effect Of Zr-Based Amorphous Alloys

Amorphous alloys have excellent physical,chemical and mechanical properties and exhibit different irradiation behaviors from conventional alloys,which have broad application prospects in the field of nuclear energy.However,the current research on the mechanism of the irradiation effect of amorphous alloys is still insufficient.In this paper,the molecular dynamics?MD?method is used to simulate the irradiation process of amorphous alloys,and the free volume as a structural characteristic parameter is calculated to describe the microstructure evolution during the irradiation process.To accurately characterize the size and spatial distribution of free volume,a new free volume algorithm based on voronoi tessellation is designed.Then the cascading collision process of PKA in Zr₂Cu amorphous alloy model is simulated by MD method,and five typical structure models are constructed.By the calculation of the free volume,it is found that irradiation leads to a rapid increasement of free volume in the material structure,including vacancy-like defects and large size free volume.With the cascade collision process,the model removes the inhomogeneous distribution of free volume by the self-healing of structure,which is manifested as the migration and annihilation of vacancy-like defects and large size free volume.Finally the redistribution of the overall free volume caused by relaxation makes the structure almost return to the initial state,indicating the good radiation resistance.But the relaxation model still has an increase in the total free volume,which indicates the self-healing of structure cannot completely offset the radiation damage of the structure.In addition,the free volume distribution around Zr and Cu in five models is calculated by the bonding sphere.The results suggest that the free volume tends to be adjacent to the Zr atoms in the initial state.While in the cascade collision process,the vacancy-like defect has no explicit elemental dependence,but it tends to change around the Zr atoms during the migration and transformation.The average free volume around Zr atoms after irradiation increases by 5.1%,and the increase around Cu is 2.2%,indicating the microstructure change around Zr after irradiation is more obvious.It confirms the truth of the element dependence of the free volume distribution and atomic-level structural changes induced by radiation,which implies that we may select glassy materials with high structural stability against radiation by tailoring the constituent elements or the compositions in alloys.