The effects of different Sn additions (0, 0.5, 1.0, 2.0 and 3.0 wt%) on hot tearing susceptibility (HTS) of Mg–Zn–Zr alloy were studied using a “T-shaped” hot tearing mold in a pouring temperature of 700 °C and a mold temperature of 270 °C. The “Clyne–Davies” hot tearing prediction model and commercial simulation software, Procast, were used to characterize the HTS of alloys. The dendrite coherency temperature was obtained by means of differential thermal analysis. The phases evolution, microstructures and morphology of the crack zone of Mg–4Zn–xSn–0.6Zr alloys were investigated by using X-ray diffraction and scanning electron microscope. The experimental results show that the HTS of Mg–4Zn–xSn–0.6Zr alloys decreases with Sn additions up to 1.0 wt%, and then exhibits a slight increase with further Sn additions up to 3.0 wt%. The Sn additions into Mg–4Zn–0.6Zr alloy can form Mg₂Sn phase with high melting point. Appropriate addition of Sn can refine grain size, decrease the dendrite coherency temperature, increase the thickness of liquid film and the feeding ability at the end of solidification, which reduce the HTS of the alloy. However, excessive Sn addition will make Mg₂Sn aggregate and grow up, and hinder the residual liquid-phase feeding in the late solidification stage, resulting in an increase in HTS of the alloy. The order of HTS of studied alloys is: CSC(Mg–4Zn–0.6Zr) > CSC(Mg–4Zn–0.5Sn–0.6Zr) > CSC(Mg–4Zn–3Sn–0.6Zr) > CSC(Mg–4Zn–2Sn–0.6Zr) > CSC(Mg–4Zn–1Sn–0.6Zr).

使用“ T型”热撕裂模具，在浇注温度为200℃的条件下，研究了不同的Sn添加量（0、0.5、1.0、2.0和3.0 wt％）对Mg-Zn-Zr合金热撕裂磁化率（HTS）的影响。 700°C，模具温度为270°C。使用“克莱恩-戴维斯”热撕裂预测模型和商业模拟软件Procast来表征合金的高温超导。通过差热分析获得枝晶相干温度。用X射线衍射和扫描电子显微镜研究了Mg-4Zn- x Sn-0.6Zr合金裂纹区域的相演变，显微组织和形貌。实验结果表明，Mg–4Zn– x的高温超导Sn-0.6Zr合金随Sn的添加量增加至1.0 wt％而降低，然后随Sn的添加增加至3.0 wt％时呈现出轻微的增加。在Mg-4Zn-0.6Zr合金中添加Sn可以形成熔点高的Mg ₂ Sn相。适当添加锡可以细化晶粒尺寸，降低枝晶相干温度，增加液膜厚度和凝固结束时的进料能力，从而降低合金的高温超导率。然而，过量的锡添加将使Mg ₂ Sn聚集并长大，并阻碍了凝固后期的残留液相进料，导致合金的高温超导率增加。研究合金的高温超导顺序为：CSC（Mg-4Zn-0.6Zr）> CSC（Mg-4Zn-0.5Sn-0.6Zr）> CSC（Mg-4Zn-3Sn-0.6Zr）> CSC（Mg-4Zn-0.6Zr） 2Sn–0.6Zr）> CSC（Mg–4Zn–1Sn–0.6Zr）。