The effects of addition of minor amount of (0.5 wt.%) antimony (Sb) or gadolinium (Gd) and combined addition of Sb and Gd (0.5 wt.%, respectively) on the hot tearing susceptibility (HTS) of Mg-5Al-3Ca alloy were investigated experimentally using a “T-shaped” hot tearing measuring system. Various solidification parameters of the alloys were measured and calculated through thermal analysis experiments. The microstructure, grain size, and morphology of the crack zone were characterized by scanning electron microscopy and electron backscatter diffraction, and the crystal phases of the alloys were analyzed by X-ray diffraction and energy-dispersive X-ray spectroscopy. The results showed that the addition of 0.5 wt.% Gd resulted in the increase in the vulnerable temperature range (T_v) and reduced the eutectic structure content that could participate in feeding, thereby improving the HTS of the alloy. However, addition of 0.5 wt.% Sb or combined addition of Gd and Sb (0.5 wt.%, respectively) to the Mg-5Al-3Ca alloy shortened the T_v and improved the skeleton strength of the alloy, thereby reducing HTS. Moreover, significantly refined structure of Mg-5Al-3Ca-0.5Gd-0.5Sb alloy improved the feeding ability of the eutectic structure, thus the alloy exhibited the lowest HTS.

添加少量 (0.5 wt.%) 锑 (Sb) 或钆 (Gd) 以及联合添加 Sb 和 Gd（分别为 0.5 wt.%）对 Mg-5Al 热裂敏感性 (HTS) 的影响采用“T型”热裂测量系统对-3Ca合金进行了实验研究。通过热分析实验对合金的各种凝固参数进行了测量和计算。采用扫描电子显微镜和电子背散射衍射对裂纹区的显微组织、晶粒尺寸和形貌进行了表征，并采用X射线衍射和能量色散X射线光谱分析了合金的晶相。结果表明，添加 0.5 wt.% Gd 导致易损温度范围 (T _v)，降低了可参与补缩的共晶组织含量，从而提高了合金的高温超变性能。然而，向 Mg-5Al-3Ca 合金中添加 0.5 wt.% Sb 或组合添加 Gd 和 Sb（分别为 0.5 wt.%）可缩短 T v 并提高合金的骨架强度，从而降低_HTS。此外，Mg-5Al-3Ca-0.5Gd-0.5Sb合金的显着细化组织提高了共晶组织的补给能力，因此该合金表现出最低的高温超变。