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采用“T”型热裂模具研究了不同Cu含量对Mg-7Zn-x Cu-0.6Zr(x=0、1、2、3)合金热裂行为的影响。利用XRD和SEM对Mg-7Zn-x Cu-0.6Zr(x=0、1、2、3)合金进行了显微组织和热裂区域组织形貌观察。通过测量热裂纹体积表征了Mg-7Zn-x Cu-0.6Zr(x=0、1、2、3)合金的热裂倾向性。实验结果表明,Mg-7Zn-x Cu-0.6Zr(x=0、1、2、3)合金中随着Cu含量的增加,晶粒得到细化,晶界上的共晶相增多,共晶相在凝固末期对分离的枝晶起到补缩的作用,降低合金热裂倾向性。研究表明,Mg-7Zn-x Cu-0.6Zr(x=0、1、2、3)合金微观裂纹的形成是液膜、凝固收缩补偿和晶间搭桥共同作用的结果。
The effects of different Cu contents on the thermal cracking behavior of Mg-7Zn-x Cu-0.6Zr (x = 0,1,2,3) alloys were investigated using a “T” hot die. Morphology and microstructure of Mg-7Zn-x Cu-0.6Zr (x = 0,1,2,3) alloy were observed by XRD and SEM. The hot cracking tendency of Mg-7Zn-x Cu-0.6Zr (x = 0,1,2,3) alloy was characterized by measuring the volume of hot crack. The experimental results show that with the increase of Cu content, the grains are refined and the eutectic phase increases at the grain boundary in the Mg-7Zn-xCu-0.6Zr (x = 0,1,2,3) Phase in the final solidification of dendrite play the role of feeding shrinkage, reducing the hot cracking tendency of the alloy. The results show that the formation of microcracks in Mg-7Zn-xCu-0.6Zr (x = 0,1,2,3) alloy is the result of liquid film, solidification shrinkage compensation and intergranular bridging.