Simulation Of Microstructure And Mechanical Properties Of Mg Alloy Nano-Multilayer

Amorphous alloys have attracted widespread attention due to their excellent properties such as high strength,high hardness,and large elastic strain limit.However,the formation and rapid expansion of highly localized shear bands severely limits their plastic deformation ability and is difficult to meet the structural requirements.The requirements of parts have restricted the further development and application of amorphous alloys in various fields.Recent studies have shown that crystalline/amorphous dual-phase nanostructured amorphous alloys can effectively improve the plasticity of amorphous alloys,but this is at the expense of strength.Therefore,it is necessary to explore an effective method for obtaining high strength and high plasticity amorphous alloys.At the same time,shape memory alloys have higher yield strength and superplasticity due to stressinduced martensitic transformation,which provides a new perspective for obtaining betterperforming metal glass composites.In this paper,molecular dynamics simulation methods are used to construct a crystalline/amorphous multilayer film and an amorphous alloy composite material with embedded crystals,and in-depth study of the two-phase nano-amorphous alloy mechanics of two different composite materials under tensile load The influence of properties and deformation mechanism reveals the strengthening mechanism of dual-phase nanostructured amorphous alloys.The main research contents and conclusions of this article are as follows:(1)The molecular dynamics method was used to study the influence of the size and distribution of embedded grains on the mechanical behavior of the dual-phase nanocrystalline/metallic glass B2-Cu Zr/ Cu64Zr36 composite.The results show that as the size of the nanocrystalline particles increases,the deformation mode of the composite material changes from relatively uniform deformation to local deformation of a single shear band.Studies have pointed out that increasing the nanocrystalline size/volume fraction can effectively increase the peak stress of the composite,but the plasticity of the dual-phase composite is not significantly enhanced except for the smaller size nanocrystalline model.In addition,the alignment of nanocrystals leads to more serious localization of plastic strain compared to the crossed arrangement.(2)The deformation behavior of shape memory alloy/amorphous B2-Cu Zr/Cu64Zr36 nanomultilayer film under tensile load was studied by molecular dynamics simulation method.The results show that regardless of the volume fraction of the shape memory alloy,the peak stress and flow stress of the nano-multilayer film are greater than the overall amorphous alloy.The martensite transformation in the shape memory alloy phase limits the propagation of the shear band,avoids instability and out of control,and induces plastic strain strengthening.With the increase of the volume fraction of the shape memory alloy,the plastic deformation mode of the nano-multilayer film changed from the interaction of multiple shear bands to the brittle fracture caused by the aggregation of nano-pores.This means that by adjusting the volume fraction of the shape memory alloy,the plasticity and strength of the nano-multilayer film can be significantly improved.