挤压态Mg-(6～9)Al-Zn的组织性能和断裂行为分析  

Microstructure and Properties as well as Fracture Behavior of As-extruded Mg-(6～9) Al-Zn Alloy

作　　者：杜勇[1,2] 曹韩学[1] 龙思远[1] 曹凤红[1] 朱茜[1] 

机构地区：[1]重庆大学材料科学与工程学院 [2]东风汽车有限公司

出　　处：《特种铸造及有色合金》2009年第9期857-860,共4页Special Casting & Nonferrous Alloys

基　　金：国家重点基础研究发展计划(973计划)资助项目(2007CB613702)

摘　　要：通过金相观察、拉伸试验和SEM分析等方法,研究了挤压态Mg-(6～9)Al-Zn合金的显微组织和力学性能。结果表明,挤压工艺使铸态下粗大枝状晶变成均匀细小等轴晶,随着Al含量增加,合金抗拉强度、硬度和晶粒大小均呈升高趋势,而伸长率先上升后下降。AZ91综合性能最优,抗拉强度、屈服强度和伸长率分别达336.7MPa、245.3MPa和17.1%。Mg-(6～9)Al-Zn合金均表现为准解理断裂特征,适当的Al含量有利于改善合金的综合性能,但Al含量过高所形成的脆性β(Mg17Al12)相加剧了镁合金的断裂倾向。Microstructure and mechanical properties of as-extruded Mg-(6~9) Al-Zn alloys were investigated by OM (optical microscope),tensile testing and SEM (scanning electron microscope). The results indicate that coarse dendrite in as-cast alloy is transformed into fine equiaxed grain in as-extruded ones. With increasing in Al content,tensile strength,hardness and grain size are increased,however,elongation is firstly increased and then decreased. Tensile strength,yield strength and elongation of AZ91 magnesium alloy reach 336.7MPa,245.3MPa and 17.1%,respectively,showing the most desirable comprehensive properties. Fracture morphology of Mg-(6~9)Al-Zn alloys is characterized by quasi-cleavage crack. Properties of the alloys can be improved with appropriate Al contents,however,crack tendency can be enhanced as a result of creation of Mg17Al12 phase with excessive Al addition.

关 键 词：Mg-(6~9)Al-Zn合金 AL含量 组织 性能 断裂特征 

分 类 号：TG146.22[一般工业技术—材料科学与工程]