The Effect Of Pre-compression And Elements Addition On Plasticity Of Zr-based Metallic Glasses

Owing to amorphous alloys have special organization structure,the atomic are in chaos arrangement with long-range order,short-range orders,it has many better physical and chemical properties that crystalline materials do not have.Such as high strength,low Young’s modulus and good corrosion,which provide an extensive attention by a various of scholars from all over the world to amorphous all oys.But it is also because of this particular arrangements of atoms,the amorphous alloys have a worse plastic property.The way of brittle fracture which limit the engineering application of amorphous alloys.Tiny deformation processing and the addition of alloying elements can enhance the plastic property of amorphous alloys to some extent.Thus,this paper takes Cu₃₆Zr₄₈Al₈Ag₈ amorphous alloy which has good glasses forming ability（GFA）and bad plastic property as the research object,how tiny elastic pr e-compression and alloying elements Ni,Nb affect plastic properties of the mother alloy solution was investigated.The concrete process of tiny elastic pre-compression has been described.The compressive stress which is below the yield load is applied to mother alloy,so that the specimen occurs the linear elasticity or elastic deformation only,and there’s no permanent macroscopic deformation after unloading.After that,began to study the effects weight of different ways of pre-compression process parameters（different pressures,holding time and cycles）,and determine the best process.Made it as the experimental means,the microscopic mechanism of this way was characterized by Differential scanning calorimetry（DSC）.The concrete process of alloying elem ents Ni,Nb has been described.A series of(Cu_0.36Zr_0.48Al_0.08Ag_0.08)100-x Nix（x=0、2、4、6）and(Cu_0.36Zr_0.48Al_0.08Ag_0.08)100-x Nbx（x=0、1、2、4）samples which are clavate with Φ3 mm were prepared with suction-casting into a water-cooling-copper mold.The micro-structure of the samples were characterized by X-ray diffraction（XRD）,transmission electron microscope（TEM）and scanning electron microscopy（SEM）,and determine the reason of the effects of elements addition on the plastic properties of the samples.All of the mechanical performance experiment were made by universal testing machine.The results show:（1）After the pre-compression processing,Cu₃₆Zr₄₈Al₈Ag₈ samples plastic properties resulting in a corresponding changes,determine the technological parameters.And optimum the number of cycles has the greatest influence on the plastic properties of the samples,the holding time is the second,and the compressive stress has a little effects on the plasticity of the samples.（2）The contents of free volume in Cu₃₆Zr₄₈Al₈Ag₈ samples changed with the holding time,and the shear bands’ expansion and proliferation patterns are also proportional to the contents of the free volume.（3）The moderate addition of Ni could accelerate the phase separation of the samples,and lead to the occurrence of nano-scale crystal phase,enhance the plasticity of the samples.（4）The moderate addition of Nb could promote the precipitation of B2-Cu Zr toughening phase,and inhibit the occurrence of eutectoid decomposition,enhance the plasticity of the samples.