Mg–Zn–Ca alloy has a good development prospect in biomedical alloy. However, its development is restricted by large hot tearing susceptibility. Herein, the influence of Ca addition on the hot tearing susceptibility (HTS) of Mg-4Zn-xCa-0.3Zr (0.5, 1, 1.5, and 2 wt%) alloys has been studied by using thermal analysis and numerical simulation software, Procast. The “Clyne–Davies” hot tearing prediction model was improved, and Cracking Susceptibility Coefficient (CSC) was recalculated to highlight the physical significance of the model. The hot tearing zone was observed via optical microscopy and scanning electron microscopy, and the phase composition was analyzed with X-ray diffraction. The results of numerical simulations suggest that the Hot Tearing Indicator (HTI) tended to decrease with increase in Ca addition. However, the experimental results reveal that with the increase in Ca addition, the hot tearing susceptibility of the alloys first decreased with Ca addition up to 1.5 wt% and then displayed a slight increase with the addition up to 2.0 wt%. The SEM images and experimental results reveal that the thickness and ability to resist solidification shrinkage stress of the liquid membrane, quantity of the second phases, and feeding ability were all enhanced with the increase in Ca addition, thereby reducing the HTS of Mg-4Zn-XCa-0.3Zr alloys. When the Ca addition reached 2.0 wt%, the brittle calcium-containing phase forms at the grain boundary, which reduces the high-temperature strength of the matrix and the ability to resist the solidification shrinkage stress of the alloy, resulting in an increase in HTS. Therefore, when the Ca addition was 2.0 wt%, the simulation results were different from the experimental results.

Mg-Zn-Ca合金在生物医学合金中具有良好的发展前景。但是，其发展受到大的热撕裂敏感性的限制。在此，通过热分析和数值模拟软件Procast，研究了Ca添加对Mg-4Zn-xCa-0.3Zr（0.5、1、1.5和2 wt％）合金的热撕裂敏感性的影响。 。改进了“克莱恩-戴维斯”热撕裂预测模型，并重新计算了裂纹敏感性系数（CSC），以突出模型的物理意义。通过光学显微镜和扫描电子显微镜观察热撕裂区，并用X射线衍射分析相组成。数值模拟结果表明，随着Ca添加量的增加，热撕裂指标（HTI）趋于下降。然而，实验结果表明，随着Ca添加量的增加，合金的热撕裂敏感性首先随Ca添加量的增加而降低，最高为1.5 wt％，然后随添加量的增加而略有增加，最高为2.0 wt％。SEM图像和实验结果表明，随着Ca添加量的增加，液膜的厚度和抗凝固收缩应力的能力，第二相的数量以及进料能力均得到增强，从而降低了Mg-4Zn-的HTS。 XCa-0.3Zr合金。当Ca的添加量达到2.0wt％时，在晶界形成脆性的含钙相，这降低了基体的高温强度和抵抗合金的凝固收缩应力的能力，导致HTS的增加。 。因此，当Ca添加量为2.0重量％时，