Phase equilibria in the Co–Fe–La system were studied using differential thermal analysis (DTA), X-ray diffraction analysis, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Liquidus and solidus projections and a melting diagram for this system over the whole concentration range and a Scheil diagram for solidification were constructed. The ternary compound (Co,Fe) 17 La 2 (τ) (Th 2 Zn 17 -type structure) forms by peritectic reaction L + (γCo,Fe) + Co 13 La ⇄ τ at 978 °C. This ternary compound is located along the isoconcentrate of 11 at.% La and extends from 45.8 to 79.3 at.% Co. The Co 13 La phase has the widest homogeneity region and dissolves up to 43.3 at.% Fe. The solubilities of Fe in Co 5 La, Co 7 La 2 , Co 19 La 5 , and Co 3 La 2 were established to be 10.3, 9.2, 4.7, and 3.2 at.%, respectively. The solubility of Fe in Co 1.7 La 2 and CoLa 3 according to EPMA does not exceed 1 at.%. The maximum solubility of La in (γCo,Fe) and (αCo,Fe) is determined to be less than 1 at.%.

中文翻译：

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Fe-Co-La 系统的实验研究：液相线和固相线投影

使用差热分析 (DTA)、X 射线衍射分析、扫描电子显微镜 (SEM) 和电子探针微量分析 (EPMA) 研究 Co-Fe-La 系统中的相平衡。构建了该系统在整个浓度范围内的液相线和固相线投影以及熔化图和凝固的 Scheil 图。三元化合物 (Co,Fe) 17 La 2 (τ)（Th 2 Zn 17 型结构）通过包晶反应 L + (γCo,Fe) + Co 13 La ⇄ τ 在 978 °C 下形成。这种三元化合物沿着 11 at.% La 的等浓度分布，从 45.8 at.% Co 延伸到 79.3 at.% Co。Co 13 La 相具有最宽的均质区，可溶解高达 43.3 at.% 的 Fe。Fe在Co 5 La、Co 7 La 2 、Co 19 La 5 和Co 3 La 2 中的溶解度分别为10.3、9.2、4.7和3.2at.%。根据EPMA，Fe在Co 1.7 La 2 和CoLa 3 中的溶解度不超过1at.%。La 在 (γCo,Fe) 和 (αCo,Fe) 中的最大溶解度被确定为小于 1at.%。