Zr−Co−Ge三元体系在1023、1173和1373 K条件下的相平衡

Phase equilibria of Zr−Co−Ge ternary system at 1023,1173 and 1373 K

采用合金法并结合电子探针显微分析(EPMA)和X射线衍射(XRD)技术,精确测定Zr−Co−Ge三元体系在1023、1173和1373 K条件下的相平衡。合理构建Zr−Co−Ge体系在1023、1173和1373 K条件下的等温截面,分别包含29、28和26个三相区。除了证实文献中报道的5个三元化合物外,还检测到一个具有显著均匀性范围的新三元相τ,其组成在1023 K时为13.8%~19.4%Co(摩尔分数),在1173 K时为12.9%~19.0%Co(摩尔分数)和在1373 K时为12.3%~14.9%Co(摩尔分数)。而且,推断一个零变量反应发生在1023~1173 K,即τ+τ1τ4+ZrGe2。此外,第三种元素Ge在一些Co−Zr中间相中可以部分替代Co,如CoZr2和Co23Zr6,其中,Ge的最大溶解度分别可达22.8%和20.3%(摩尔分数)。

Phase equilibria of the Zr−Co−Ge ternary system at 1023,1173 and 1373 K were precisely measured via alloy sampling associated with electron probe microanalysis(EPMA)and X-ray diffraction(XRD)techniques.The isothermal sections in the Zr−Co−Ge system were appropriately constructed,containing 29,28,and 26 three-phase regions at 1023,1173,and 1373 K,respectively.Except for confirming the five ternary compounds previously reported in the literature,a new ternary phaseτwas detected with a remarkable homogeneity range,consisting of 13.8−19.4 at.%Co at 1023 K,12.9−19.0 at.%Co at 1173 K and 12.3−14.9 at.%Co at 1373 K.And,an invariant reaction was deduced to occur at a temperature between 1023 and 1173 K,i.e.,τ+τ1τ4+ZrGe2.Besides,the third element Ge can partly substitute Co in some Co−Zr intermediate phases,e.g.,CoZr2 and Co23Zr6 where the maximum solubility of Ge can separately reach up to 22.8 at.%and 20.3 at.%,respectively.