Nb-Ni-Ti系低Ti侧三元化合物及其相平衡

Ternary Compound and Relative Phase Equilibria in the Low-Ti Side of Nb-Ni-Ti System

采用合金平衡组织结构分析法,利用扫描电镜组织观察和能谱成分分析、电子探针定量成分分析以及X射线衍射结构分析,并结合热分析,对Nb-Ni-Ti系低Ti侧化合物XB及其相关相平衡进行了研究.结果表明,在Nb-Ni-Ti三元系1000℃和1100℃等温截面相图中都存在着三相区XB+(Nb)+TiNi,化合物XB可与Nb基固溶体(Nb)和TiNi相保持固态相平衡直到约1133℃.Nb-Ni-Ti三元系在1 133℃发生三相共晶转变LTiNi+XB;由于液相L的形成,XB相不再与TiNi相和Nb基固溶体平衡.1 150℃时Nb-Ni-Ti三元系等温截面相图中存在着XB+(Nb)+L三相区,XB相与Nb基固溶体和液相平衡共存.

The phase transformation and phase equilibria related with the ternary compound XBin the low-Ti side of Nb-Ni-Ti system were systemically investigated through the equilibrated alloy method by using the scanning electron microscopy（SEM） assisted with energy dispersive spectroscopy of X-ray（EDS）,electron probe microanalysis（EPMA）,X-ray diffraction（XRD）and differential scanning calorimetry（DSC）.It has been shown that the three-phase field XB＋（Nb） ＋TiNi exists at both 1000 ℃ and 1100 ℃ isothermal sections of the phase diagram in the Nb-Ni-Ti system.The compound XBcould be in solid-state equilibrium with the Nb-based solid solution（Nb） and the TiNi phase till about 1 133 ℃.There exists the eutectic phase transformation L←→TiNi ＋ XBat 1 133 ℃ in the Nb-Ni-Ti system.As the liquid forms,the compound XBcould not be in equilibrium with the Nb-based solid solution and the TiNi phase.The three-phase field XB＋（Nb） ＋ L exists at 1 150 ℃ isothermal sections of the phase diagram in the Nb-Ni-Ti system,XBkeeps phase equilibrium with the liquid and the Nb-based solid solution.