Experimental Investigation Of Phase Equilibria In Zr-Ni-Ge Ternary System

Zirconium-based amorphous alloys have attracted much attention because of their excellent mechanical properties.As the typical representative,Zr Ni-based amorphous alloy has unique catalytic effect and hydrogen absorption ability,and has been widely used in fuel cell,biomedical,atomic force microscope（AFM）and coolant flow circuit in nuclear reactor engineering.The corrosion resistance of Zr Ni-based amorphous alloys can be improved by adding Ge to the Zr Ni-based amorphous alloys.The phase diagram is also closely related to the design of amorphous alloy composition.As a map of material design,the phase diagram can predict the amorphous forming ability of the alloy.In order to improve the phase equilibrium information of the ternary system of Zr Ni,reasonably predict the process and mechanism of interface microstructure evolution of typical alloys during the solidification process and welding process under real conditions,and better understand the existence state of the third group in Zr-Ni alloy and its influence on the formation and stability of alloy phase,It is necessary to study the phase relationship of Zr-Ni-Ge ternary system.In this work,the phase relationship of the Zr-Ni-Ge ternary system was studied by using alloy sampling approaches.The main research work is as follows:（1）Crystal structureτ₂ of was determined,which belongs to space group Pbcm（No.57）with cell parameters a=11.315（1）?,b=5.444（9）?and c=5.355（1）?.And the chemical formula ofτ2 was redefined as Zr_0.98Ni Ge_2.94（2）Phase equilibria at 973,1173 and 1373 K in Zr-Ni-Ge ternary system have been measured through alloy sampling.According to the results from electron probe microanalysis（EPMA）and X-ray diffraction（XRD）,constituent phases coexisting in the annealed alloys were determined.The isothermal section of the Zr-Ni-Ge ternary system at 973,1173 and 1373 K were constructed,consisting of 26,26 and 23 three-phase regions,respectively.It is worthy that,except for the formerly reported ternarycompounds,τ1(Zr₆Ni₁₆Ge₇),τ2(Zr₂₂Ni₂₀Ge₅₈),τ3（Zr₃Ni₄Ge₄）,τ4（Zr Ni Ge）andτ5(Zr₂Ge_0.54Ni_0.46),a new ternary phase namedτ6 with composition of Zr₃₉Ni₁₈Ge₄₃ was primarily detected in this work.