Effect Of Microalloying On Plastic Deformation Of Cu-Zr-Al Amorphous Alloy

Metallic glasses have attracted wide attention due to their unique physical,chemical and mechanical properties.However,the application of amorphous alloys as structural or functional materials in practical production is still faced with the key problem of poor plasticity at room temperature.The results show that there is a positive enthalpy of miscibility between the alloy components,which can lead to the inhomogeneity of the local chemical composition of the matrix and even the phenomenon of phase separation.Therefore,it is of theoretical and practical significance to systematically study the effects of trace elements Fe and Nb on the glass-forming ability and mechanical properties of Cu-Zr-Al alloy system.In this paper,Cu_(47.8)-xZr_46.2Al₆Fe_x(x=0,0.8,1.2,1.6)and Cu_(48)-xZr_46.2Al_5.8Nb_x(x=0,1.5,3,4.5)bulk amorphous alloys were prepared by copper mold spray casting,The phase composition,thermal parameters,room temperature compressibility,fracture morphology,microstructure and microhardness of the as cast alloy were analyzed by X-ray diffraction,synchronous thermal analyzer,universal testing machine,scanning electron microscope,high-resolution transmission electron microscope and nano indentation system,and the detailed deformation mechanism is discussed.The research results show that in the Cu_(47.8-x)Zr_46.2Al₆Fe_x(x=0,0.8,1.2,1.6)alloy system,as the Fe content increases,the thermal stability of the amorphous alloy decreases.Compression performance at room temperature shows that the plasticity of the alloy gradually increases with the increase of Fe content.When the Fe content is1.2%,its room temperature plasticity is the best,reaching 7.23%.The results of high-resolution transmission electron microscopy show that Cu_46.6Zr_46.2Al₆Fe_1.2 alloy presents a typical amorphous structure.The reason for the increase in plasticity at room temperature may be due to the positive mixing enthalpy between Fe and Cu,which leads to the composition/freeness of the matrix.It is caused by the increase in the degree of unevenness of the volume distribution.In the Cu_(48-x)Zr_46.2Al_5.8Nb_x(x=0,1.5,3,4.5)alloy system,the thermal stability and glass forming ability of amorphous alloys also decrease with the increase of Nb content.Compression plasticity at room temperature increases with the increase of Nb content.When the content of Nb is 3%,its room temperature plasticity reaches 11.98%.The results of high-resolution transmission electron microscopy showed that:Cu₄₅Zr_46.2Al_5.8Nb₃ alloy system room temperature plasticity increase is mainly due to the nano-scale phase separation inhomogeneous microstructure inside the alloy.The nanoindentation experiment further confirmed that as the Nb content in the system increases,the degree of inhomogeneity of the alloy microstructure gradually increases,and this often provides more positions for the nucleation of the shear band,and finally Contribute to the plastic deformation of the material.