Micro-Mechanism Study Of Influence Of Pre-Compression On Mechanical Properties Of Zr-Based Amorphous Alloys

As a new material,amorphous alloys have a number of attractive properties,such as high strength and hardness,wide elastic range,and so on.However,the lack of tensile plasticity at room temperature limits the application of amorphous alloys as engineering materials.In order to understand the microscopic mechanism during the deformation process,the molecular dynamics simulation method was used to study the relationship between the free volume,shear transition zones and shear bands of Zr₂Cu amorphous alloy during tensile deformation via LAMMPS software.After that,the influence of pre-compression on the micro-mechanism of mechanical properties of Zr₂Cu amorphous alloy was investigated.The tensile process of amorphous alloys was studied.The results show that there is a critical free volume value of 4.7%in the amorphous alloy.When the free volume of a specific region is larger than this value,the region softens and a shear transition region is generated.As the strain increases,the different shear transition zones are joined together to form a primary shear bond along 45°under the combined influence of the shear stress and the free volume concentration difference,corresponding to a steep drop in stress.As the strain continues to increase,the primary shear band expands into a mature shear band causing catastrophic brittle fracture.In addition,pre-compression is performed in the Z-direction of Zr₂Cu amorphous alloy.The results show that pre-compression will activate some areas of the amorphous alloy.In the subsequent X-direction stretching process,these activation areas will not only increase the amount of shear transition zones,but also hinder the expansion of shear transition zones.The"cross"shear bands are generated in the 45°and 135°directions,which interact with each other.And the strain can be more homogeneously distributed in the amorphous alloy,avoiding stress localization,and effectively improving the mechanical properties of the amorphous alloy.The study of the free volume of the deformation process shows that the free volume increases rapidly after softening,and saturation occurs after quasi-static flow strain,and this value is close to the free volume value of the liquid,indicating that the yield of the amorphous alloy has a certain relationship with the glass transition.