Comparative Study On Nanomechanical Properties Of Amorphous Alloy And Crystalline Alloy In Pd-W-Si System

Amorphous alloy(other name: metallic glass)has excellent mechanical properties,such as high fracture strength,good wear resistance,high hardness,and large elastic deformation limit.Therefore,metallic glass has applications in many fields such as military and national defense,aerospace,rail transit,and food production.However,the preparation of bulk metallic glass is more difficult,making it difficult to be widely used.On the other hand,metallic glass also has shortcomings: at room temperature,most metallic glasses are brittle,and the macroscopic plastic deformation ability is not satisfactory,which also restricts the development of metallic glasses.Therefore,studying the glass forming ability and deformation failure mechanism of amorphous alloys can provide theoretical support for the design of metallic glasses that are easy to prepare and have good plasticity,which has extraordinary engineering value.To this end,this article first uses magnetron combined sputtering to create a Pd-W-Si ternary alloy library with crystalline and amorphous structures,and then uses XRD technology to analyze the phase structure of each alloy in the alloy library,and then uses EDX technology to obtain the element composition of each sample in the alloy library,and finally use the nanoindenter/scratch instrument to perform indentation and creep experiments on each alloy in the alloy library to characterize the mechanical properties of each alloy.By analyzing the relationship between the phase structure,element composition and mechanical properties of the Pd-W-Si ternary alloy library,the influencing factors of the glass forming ability and plastic deformation ability of the amorphous alloy can be obtained.Based on the above experiments,the main conclusions obtained in this article are as follows:(1)In the Pd-W-Si ternary alloy system,as the content of Si element with a smaller atomic radius increases,the glass forming ability of the system will increase.This indicates that increasing the Si element concentration can improve the glass forming ability of the Pd-W-Si system,that is,the effective atomic packing and the mismatch of atomic size enhance the glass forming ability.(2)In the Pd-W-Si ternary alloy system,the values of the material plastic deformation response parameters E_r~2/H and W_p/W_t show that the amorphous alloy has a smaller fluctuation range than the crystalline alloy,that is,the element composition depend is much weaker.This shows that there is a significant difference in the plastic deformation mechanism of the two,that is,the plastic strain adjustment ability of the amorphous alloy formed by the shear band is lower than the plastic strain adjustment ability of the crystalline alloy formed by the dislocation slip.(3)In the Pd-W-Si ternary alloy system,based on the well-known effective cluster accumulation model,a set of atomic accumulation models that depend on changes in alloy composition are proposed to explain the observed structure-property relationship to reveal the evolution of the structure of different alloy components in the crystal system.(4)In the Pd-W-Si ternary alloy system,a continuous strong external force is used to act on the amorphous alloy.Amorphous alloys that contain more Si elements to form a rigid metalmetalloid bond will suffer from the rigid metal-metalloid bond.Brittle fracture causes more severe plastic deformation.