Effect Of Heavy Rare Earth Elements Addition On The Glass Forming And Properties Of Cu-Zr-Al Alloy

In this paper,on the basis of Cu-Zr-Al amorphous alloy,the control of heavy rare earth elements Dy,Tb and Gd on its amorphous formation ability,thermal stability,mechanical properties and corrosion resistance were investigated.Specific research contents are as follows:Firstly,the regulation of the addition of Dy,Tb and Gd on the amorphous formation ability of Cu₅₀Zr₄₆Al₄ alloy was studied.1.5mm and 3mm Cu_50-xZr₄₆Al₄RE_x（RE=Dy,Tb,Gd;x=0,1,2,3,4）rod-like amorphous alloy,The critical size（d）of the amorphous alloy was obtained by analyzing the structure of the sample with XRD diffractometer.A series of thermodynamic parameters were obtained by simple calculation.The width of the supercooled liquid region△T_x（△T_x=T_x-T_g）andγ=T_x/（T_g+T_l）can be used to judge the amorphous forming ability of the alloy.The results show that with the addition of heavy rare earth elements Dy,Tb and Gd,the width of the supercooled liquid phase region increases as the glass transition temperature of the alloy system decreases obviously.The maximumγparameter value and critical size are obtained by adding 1at.%Dy,Tb and 3at.%Gd,indicating that proper addition of rare earth elements is beneficial to the improvement of the amorphous forming ability of the alloy.Then,Cu_50-xZr₄₆Al₄RE_x（RE=Dy,Tb,Gd;x=0,1,2,3,4）.The yield strength,elastic strain,fracture strength and plastic strain of the alloy were obtained by calculation.The fracture characteristics of the sample were observed.The results show that proper amount of Dy,Tb and Gd can effectively improve the strength and plasticity of Cu-Zr-Al alloy.The plastic strain of Cu₄₈Zr₄₆Al₄Gd₂ reaches 9.75%,while the fracture strength of Cu₄₉Zr₄₆Al₄Dy₁ reaches 2.062GPa.Compared with Cu₅₀Zr₄₆Al₄,the plastic deformation capacity and fracture strength of Cu₄₉Zr₄₆Al₄Dy₁ increase by nearly 20 times and 34%.On this basis,hardness tests were carried out on all alloy samples,and it was found that the hardness andγparameters showed a similar trend with the change of the content of rare earth elements.This result indicates that there may be a certain correlation between the amorphous forming ability and hardness.From the radial distribution of hardness of the alloy,the amorphous alloy with the addition of rare earth elements presents greater radial inhomogeneity,which is conducive to the improvement of plastic deformation ability of the alloy.Finally,the corrosion resistance of Cu-Zr-Al amorphous alloy was investigated.It was found that Cu₅₀Zr₄₆Al₄ amorphous alloy in 3.5%Na Cl solution did not generate passivating film,and the corrosion rate was accelerated.However,the addition of Gd has little effect on its corrosion performance,and cannot effectively regulate its corrosion performance.