| The bulk amorphous alloy has excellent mechanical properties such as high hardness,high strength and high elastic modulus,which makes it a new type of material with wide application prospect.However,there has no obvious plastic deformation of bulk amorphous alloys at room temperature,which restricts the further development of amorphous alloy as engineering structural materials.The plastic deformation of the bulk amorphous alloy is carried out in the form of shear bands.So the amount of shear bands involved in deformation is closely relatede to the plastic deformation ability of amorphous alloys.The spatial proliferation of shear bands during deformation can increase the number of shear bands.So evolution of the bulk amorphous alloy and the expansion and spatial propagation of the shear zone under the action of temperature and stress are studied in this paper.The effects of temperature and stress on plastic deformation were investigated.The room temperature creep behavior of alloy at micro and nano scale was studied by conducting nano indentation test on Zr52.5Cu17.9Ni14.6Al10Ti5(Vit.105)and Mg58Cu30Y10 bulk amorphous alloys.The experimental results show that the room temperature creep behavior of the two alloys is related to loading enviorment(such as loading and loading rate)at the micro and nano scale,and shows obivous component dependence.For example,the larger the load and the faster the loading rate,the more obvious the creep phenomenon.Under the same conditions the creep displacement of Mg-based amorphous alloy is larger than that of Vit.105 alloy.The effect of temperature induced on the microstructure evolution and the plastic deformation of amorphous alloy was studied on Vit.105 bulk amorphous alloy.The experimental results show that the stress induced structural evolution of the amorphous alloy is closely related to the environmental temperature.When the sample is pretreated by 40 oC,its free volume increment is maximum.The larger free volume increment provides a large amount of nucleation space for the space transformation of the shear band during the deformation process of the amorphous sample,which promotes the proliferation of the shearband and improves the plastic deformation ability of the amorphous alloy.With the temperature increasing,the free volume increment decreased,weakened shear zone proliferation ability and space,and the occurrence of the droplet and the liquid back makes the hindrance of shear band decreases in the process of expansion.Therefore,the plastic deformation ability is reduced. |
