The Cluster Electrochemical Potential Of Cu-Zr Metallic Glasses Studied By Molecular Dynamics

As a new type of metal materials,the atomic arrangement of metallic glasses(MGs)is special,hence MGs can exhibit many excellent properties,such as high strength and hardness,excellent corrosion resistance and soft magnetic properties,to make it in wide application of industry and scientific research.However,owning to the absence of long range order,the thermodynamic mechanism of MGs structure has not well understood even though varieties of researches focusing on the structure rules of MGs have been carried out,let alone the correlation between structural feature and mechanical properties,which seriously restrict the further research on MGs.In view of above issues,this paper makes a theoretical study on the structural features and mechanical properties of MGs.The structural features of three kinds of Cu-Zr binary MGs(Cu46Zr54,Cu50Zr50,and Cu64Zr36 MGs)were studied by employing the molecular dynamics(MD)simulation.Computational results show that there is a cooperative relationship between the coordination number(CN),the combination of the coordination atoms and the atomic radius.In addition,the atomic clusters defined by Voronoi polyhedron are confirmed nearly spherical.Therefore,the radius of the cluster can be regard as an effective parameter to calculate the cluster electrochemical potential(CECP).The calculation on the electrochemical potential(ECP)of the atoms and clusters with different sizes shows that the ECP of two types of atoms is largely different,while the ECP of clusters with different sizes are highly concentrated.The great change of the ECP distribution when electronic system changed from atoms to clusters shows that the electrochemical potential equilibrium state of the MGs is achieved at atomic cluster level.Further analysis on random structures which were quenched under different temperatures shows that the CECP in the MGs tends to maximum uniform distribution,and the atomic arrangement of MGs was dominated by the maximum uniform distribution rule.The calculation on CN and CECP of deformed MGs shows that the plastic deformation occurs and the shear zone begins to form when the strain is more than 0.5%.In all clusters centered by each component atoms,the clusters with preferred CN are the most stable.Concretely,clusters centered by Cu atoms in Cu-Zr MGs are more stable than that clusters centered by Zr atoms.Plastic deformation makes the CECP no longer uniformity distribution,while the strain rate has no obvious effect on this change.