The Study On Structure Evolution Of Cu₅₀Zr₅₀ Amorphous Alloy Under High Pressure By Molecular Simulation

Amorphous alloys have more excellent properties than crystalline materials because of their unique structural features.In this paper,the classical molecular dynamics simulation software——Lammps was used to perform high-pressure deformation of Cu₅₀Zr₅₀ amorphous alloy and Cu₅₀Zr₅₀ ideal crystal under the same conditions respectively.Atomic level was characterized by pair distribution function,bond pair analysis technique and local atom strain.At the same time,the relationship between the amorphous alloy and the ideal crystal is explored in order to establish the relationship between the two different structures of the amorphous alloy and the ideal crystal.The evolution process of Cu₅₀Zr₅₀ amorphous alloy under different pressure was analyzed by the analysis of pair distribution function.The results show that when the pressure is increased to 50 GPa,the system still retains the amorphous structure,and the whole system tends to bond to the cluster with large exponent and odd order symmetry.The average atomic volume of each pressure system is obtained,which get the relationship curve of volume-pressure.With the increase of the pressure,the mean atomic volume gradually decreases and the curves change continuously,which shows that there is no phase transition in the whole high pressure process.At the same time,the bulk elastic modulus of the alloy is 125.8GPa by fitting the Bridgman equation,which is in accordance with the reported value.The simulation has carried out for ideal crystal under the high-pressure among which are 10 GPa,20GPa,…,120 GPa,respectively,and calculated the V-P variation.We found that the curve changed continuously before 80 GPa.However,when the pressure rose between 80 GPa to 90 GPa,the curve is changed down abruptly and phase change occurs.After 100 GPa,the curve parallel to the amorphous V-P curve,which indicates that the phase transition is complete and the new structure is amorphous.This conclusion can be obtained by splitting the second peak of the bimodal distribution function.And then unloading the pressure of the amorphous structure abated by phase transition induced by high pressure and making it fully relaxation,which second peak of the pair distribution fraction is splitting and the alloy remains amorphous,indicating that the process of high pressure induced amorphization is irreversible.The new amorphous structure energy and volume different from 1K/ps rapid cooling of the amorphous structure,the phenomenon of the establishment of a new amorphous alloy preparation method,and this newly prepared amorphous structure can be stable at room temperature.