| Research of Ti-Ni-Nb ternary phase diagram, which originated in the Ni-base super alloy development is began from the Ni-rich center. With the development of the wide lagging shape memory alloy, the composition of the phase equilibrium get studyed. But the information of the part of the hyperthermia phase equilibrium is limited, cannot meet the needs of the Ti-Ni-Nb of amorphous alloy and filtration membrane alloy hydrogen related alloy design. The credibility of the system thermodynamics parameter due to lack of experimental data.The isothermal section of the Ti-Ni-Nb ternary system in low Ti side at 1000℃has been investigated use metallography and the method of diffusion couples, mainly by optical microstructure analysis and scanning electrom microscopy, energy spectrum analysis and electron probe microanalysis, X-ray diffraction and transmission electron microscope diffraction structural analysis, and with the aid differential thermal analysis.The results of the study show that:A ternary compounds XE with the composition 10 at.%Ti-80 at.%Ni-10 at.%Nb is in the Ni-rich corner, The crystal structure of the XE-phase is p-hexagonal, the crystal parameters are a=0.512nm, c=0.8366nm. The XE-phase has two-phase equilibrium with Ni-based solid solutions-phase.A ternary compounds XB with the composition 14 at.%Ti-46 at.%Ni-40 at.%Nb is in the low Ti side, Its melting point was 1359℃. The crystal structure of the XB-phase is p-hexagonal, the crystal parameters are a=0.492nm,c=2.664nm.The solubility of Nb in the Ni solid solution increases with the addition of Ti, the highest solubility of Nb in the Ni solid solution at 1000℃is about 11.7at%. The solubility of Ti and Nb is higher to 14.3 at%. and the hightest solubility of Ti in the Ni3Nb is about 7.9at.%. The isothermal section of the Ti-Ni-Nb ternary system in low Ti side at 1000℃has four three-phase region:(Ni)+Ni3Nb(Ti)+XE. Ni6Nb7(Ti)+XD+Ni3Nb(Ti), XB+XA+XD and XB+XA+TiNi。... |
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