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利用TEM和HRTEM研究Mg-8Zn-4Al-1Ca合金的时效微观组织。结果表明:Mg-8Zn-4Al-1Ca合金较Mg-8Zn-4A1合金时效硬度显著增高。Mg-8Zn-4Al-1Ca合金在160°C时效16 h,有大量的盘状Ca2Mg6Zn3相沉淀弥散析出,此外,合金的微观组织中还存在晶格畸变、蜂窝状的莫尔条纹、刃型位错及位错环;经48 h时效后合金中沉淀相为粗大的盘状沉淀相和细小、弥散的粒状沉淀相;经227 h时时效后后,其组织中存在大量MgZn2相和Ca2Mg6Zn3相。因此,在Mg-8Zn-4Al-1Ca时效160°C的合金中添加Ca元素能有效提高合金的时效硬度及促进MgZn2强化相的生成。
TEM and HRTEM were used to study the aging microstructure of Mg-8Zn-4Al-1Ca alloy. The results show that the aging hardness of Mg-8Zn-4Al-1Ca alloy is significantly higher than that of Mg-8Zn-4A1 alloy. Mg-8Zn-4Al-1Ca alloy aged at 160 ° C for 16 h, a large number of disc-shaped Ca2Mg6Zn3 phase precipitation precipitation, in addition, there are lattice distortion in the microstructure of the alloy, cellular Moiré fringes, edge bit After 48 h aging, the precipitated phase in the alloy is coarse disc-shaped precipitated phase and fine and dispersed granular precipitated phase. After aging at 227 h, a large amount of MgZn2 phase and Ca2Mg6Zn3 phase exist in the microstructure. Therefore, adding Ca into the alloy with Mg-8Zn-4Al-1Ca aging at 160 ° C can effectively improve the aging hardness and promote the formation of MgZn2-reinforced phase.