Effect Of Ta Substitution Ni On Glass Form Ability And Properties Of ZrCuAlNi Bulk Amorphous

Based on the amorphous alloy composition of Zr₅₆Cu₂₃Al₁₀Ni₁₁,the amorphous alloy composition of Zr₅₆Cu₂₃Al₁₀Ni_11-xTa_x（x=0,0.5,1,1.5,2,2.5at.%）system was designed by replacing Ni with trace Ta.Amorphous alloy bars with different diameters were prepared by the combination of non-consumable electric arc smelting and copper die casting.The structure of amorphous alloy was characterized by X-ray diffraction（XRD）and transmission electron microscopy（TEM）.The thermal properties of amorphous alloys were analyzed by differential scanning calorimetry（DSC）.The corrosion resistance of amorphous alloys was tested by electrochemical workstation.The compressive mechanical properties were tested by Instron universal material testing machine.The fracture characteristics and fracture mechanism were analyzed by SEM.The results of XRD and TEM analysis show that the ability of amorphous formation of Zr₅₆Cu₂₃Al₁₀Ni₁₁ amorphous alloy can be improved and the critical size can be increased by replacing Ni with Ta.Among them,the critical sizes of Zr₅₆Cu₂₃Al₁₀Ni₁₀Ta₁and Zr₅₆Cu₂₃Al₁₀Ni_9.5Ta_1.5amorphous alloys are up to 6mm.Through DSC test and analysis,it can be seen that the glass transition temperature T_g,crystallization temperature T_x,supercooled liquid regionΔT and reduced glass transition temperature T_rg of Zr₅₆Cu₂₃Al₁₀Ni_11-xTa_x（x=0,0.5,1,1.5,2,2.5at.%）amorphous alloy increase at first and then decrease with the increase of Ta element.Among them,the amorphous alloy with x=1%and 1.5%composition has the largest supercooled liquid regionΔT=73k and the largest reduced glass transition temperature T_rg=618,showing good glass forming ability and thermal stabilityThe compressive mechanical properties of Zr₅₆Cu₂₃Al₁₀Ni_11-xTa_x（x=0,0.5,1,1.5,2,2.5at.%）amorphous alloy were analyzed.It was found that the fracture strength and elastic strain increased with the increase of Ta content.Vickers hardness test showed that the hardness value of amorphous alloy increased monotonously with the increase of Ta content when the diameter of the sample was 3 mm and 5 mm.When the diameter of the sample was 6 mm,the hardness value showed discrete distribution,which may be related to the homogeneity of the composition.The analysis of the compression fracture of the amorphous alloy by SEM shows that the compression specimen has shear fracture in the range of 39°～42°.With the increase of Ta content,the choroid pattern on the fracture surface changes from non-uniform distribution to uniform distribution,indicating that its deformation ability also increases gradually.Through the analysis of electrochemical corrosion polarization curve,it is found that the corrosion potential ecoor increases gradually and the corrosion current density icoor decreases gradually after adding Ta element,which shows that the increase of Ta element improves the corrosion resistance of amorphous alloy.