Gd has higher solid solubility than Y in Mg, which has a greater influence on the mechanical properties of the alloy, but there is little research on its hot tearing. In this paper, the coupling behavior of solidification and hot tearing of Mg–xZn–2xGd (x = 0.5, 1, 1.5, 2 at.%) alloy was studied, and its micro-mechanism was revealed. It is found that the microstructure of Mg–2xGd–xZn alloy is composed of α-Mg, LPSO and W phase. With the increase of x, α-Mg grain is refined, the second phase content is increased, and the hot tearing susceptibility is decreased. Under the same composition, Gd has a better effect on reducing the hot tearing tendency than Y. Further studies show that with the increase of x, the relative content of residual liquid phase between α-Mg grains increases after crystallization, and its feeding ability to local shrinkage of solid phase is enhanced. In addition, the morphology of LPSO precipitated along the grain boundary is wedged into both sides of α-Mg matrix, which is considered to be helpful to prevent the propagation of hot cracking along the grain boundary, which is another important reason to reduce the hot cracking sensitivity of the alloy.

Gd在Y中的固溶度比Y高，这对合金的机械性能影响更大，但对其热撕裂的研究很少。本文研究了Mg – x Zn–2 x Gd（x  = 0.5、1、1.5、2 at。％）合金的凝固与热撕裂耦合行为，并揭示了其微观机制。研究发现，Mg–2 x Gd– x Zn合金的显微组织由α-Mg，LPSO和W相组成。随着x的增加，α-Mg晶粒细化，第二相含量增加，热撕裂敏感性降低。在相同的组成下，Gd比Y具有更好的降低热撕裂趋势。进一步的研究表明，随着x的增加，α-Mg晶粒之间残余液相的相对含量在晶化后增加，并且其进料能力固相的局部收缩增加。另外，沿晶界析出的LPSO的形态被楔入α-Mg基体的两侧，被认为有助于防止热裂纹沿晶界的传播，这是减少热的另一个重要原因。合金的开裂敏感性。