The isothermal section in the Mg–Cu rich region of Mg–Cu–Ca ternary system at 300 °C was investigated in the present work. Two ternary compounds named as P1 and Mg_25-xCu₇₅Ca_x were observed. The solid solubility limit of the compound Mg_25-xCu₇₅Ca_x was found to be 8.29 ≤ x_Ca ≤ 15.71 with a constant value of about 75 at. % Cu at 300 °C. A narrow solid homogeneity range of the compound P1 was found to be Mg₁₉Cu₄₀Ca₄₁ to Mg₂₁Cu₄₂Ca₃₇ (in at. %). The maximum solid solubility of Ca in the terminal compound MgCu₂ (C15) was determined to be 10.20 at. % at 300 °C. The maximum ternary solid solubility of binary terminal compounds Mg₂Ca, Mg₂Cu, Cu₅Ca and CuCa were determined to be less than 2 at. %. For the more, thermodynamic modeling of the Cu–Ca binary and Mg–Cu–Ca ternary systems have been carried out by calculation of phase diagram (CALPHAD) method. The liquid solution was described using the modified quasi-chemical model (MQM). The compound energy formalism (CEF) was used for the solid phases. A self-consistent thermodynamic database of the Mg–Cu–Ca ternary system have been constructed in the present work.

本工作研究了 300 °C 下 Mg-Cu-Ca 三元体系的 Mg-Cu 富集区的等温截面。观察到两种名为 P1 和 Mg _25-x Cu ₇₅ Ca _{x 的}三元化合物。发现化合物 Mg _25-x Cu ₇₅ Ca _x的固溶度极限为8.29 ≤ x _Ca ≤ 15.71，恒定值约为 75 at。300 °C 时的 % Cu。发现化合物 P1 的窄固体均质范围为 Mg ₁₉ Cu ₄₀ Ca ₄₁至 Mg ₂₁ Cu ₄₂ Ca ₃₇（以原子百分比计）。Ca在末端化合物MgCu中的最大固溶度₂ (C15) 被确定为 10.20 at。% 在 300 °C。二元末端化合物Mg ₂ Ca、Mg ₂ Cu、Cu ₅ Ca和CuCa的最大三元固溶度被确定为小于2at。%。此外，通过相图计算 (CALPHAD) 方法对 Cu-Ca 二元和 Mg-Cu-Ca 三元系统进行了热力学建模。使用修正的准化学模型 (MQM) 描述液体溶液。复合能量形式（CEF）用于固相。在目前的工作中已经构建了一个自洽的 Mg-Cu-Ca 三元系统热力学数据库。