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利用SEM、EPMA、XRD、DSC对Nb-Ni-Ti系低Ni侧1000℃的液相相关相平衡进行了研究。结果表明,1000℃时,在Nb-Ni-Ti系低Ni侧存在着一个可与(Nb,bTi)连续固溶体和TiNi化合物相平衡的液相区;该液相区源自Ti-Ni二元系,延伸至Nb含量3.7%(原子分数)。而二元化合物TiNi在1000℃时则可以溶解约8.0%Nb。1000℃时,Nb-Ni-Ti系低Ni侧等温截面相图中存在2个三相区Liquid+(Nb,bTi)+TiNi和(Nb,bTi)+TiNi+XB,XB是成分为34.0Nb-44.9Ni-21.1Ti的六方结构化合物;这2个三相区之间则是宽阔的(Nb,bTi)+TiNi两相区。在该两相区内,连续固溶体(Nb,bTi)中的Ni含量变化不大、约为3%,Ti含量的变化范围为6.6%~39.9%。而3.7%Nb的溶入未能使二元化合物Ti_2Ni相的稳定存在温度提高到1000℃。
The liquid-phase phase equilibria at 1000 ℃ on the low Ni side of Nb-Ni-Ti system were investigated by SEM, EPMA, XRD and DSC. The results show that at 1000 ℃, there is a liquid phase in the low Ni-side of Nb-Ni-Ti system that can balance with (Nb, bTi) solid solution and TiNi compound. The liquid phase is derived from Ti-Ni binary Department, extending to the Nb content of 3.7% (atomic fraction). The binary compound TiNi can dissolve about 8.0% Nb at 1000 ℃. At 1000 ℃, there are two three-phase regions of Liquid + (Nb, bTi) + TiNi and (Nb, bTi) + TiNi + XB in the low Ni side isothermal section of Nb-Ni- 44.9Ni-21.1Ti hexagonal structure compounds; between the two three-phase region is wide (Nb, bTi) + TiNi two-phase region. The content of Ni in the continuous solid solution (Nb, bTi) did not change much in the two-phase region, about 3%, and the Ti content varied from 6.6% to 39.9%. However, the dissolution of 3.7% Nb failed to increase the stable existence temperature of binary Ti_2Ni phase to 1000 ℃.