(山东大学 材料液态结构及其遗传性教育部重点实验室，
济南 250061)
摘 要: 研究了熔体过热和热速处理对AZ91铸造Mg-Al-Zn合金组织和力学性能的影响。在含有Mn和钢坩埚内壁未刷有涂料的前提下，熔体温度(820℃)不够高时，会引起晶粒的粗化；熔体温度(870℃)足够高时，镁合金结晶晶核的增加引起了基体组织的细化，同时组织中的γ强化相比未高温过热时弥散、均匀；热速处理后组织部分保留了高温过热时的特性，从而使镁合金的力学性能和铸件质量得到提高。
关键字: 镁合金；热速处理；晶粒细化
microstructure and mechanical
properties of cast Mg based alloy
（The Key Laboratory for Liquid Structure and Heredity of Materials of
Ministry of Education, Shandong University, Ji′ nan 250061, China）
Abstract:The effects of melt superheating and thermal rate treatment technique on the microstructure and properties of AZ91 cast magnesium alloy were investigated. When the alloy contains Mn element and the crucible had no coating o n the internal surface, the alloy grains thicken at the relatively low melt temperature(820℃). However, the grains refine at the high enough melt temperature (870℃), and the strengthening γ phrase is more dispersive and uniform. The microstructure of AZ91 alloy keeps some characteristics of the high temperature melt after thermal rate treatment, which improves the mechanical properties and casting quality of magnesium alloy.
Key words: magnesium alloys; thermal rate treatment; grain refinement
