挤压态Mg-9Li-3Al-xSr镁合金的微观组织与力学性能  

Microstructure and mechanical properties of extruded Mg-9Li-3Al-xSr alloys

作　　者：杨艳[1] 彭晓东[1,2] 李俊辰[1] 谢卫东[1,2] 魏国兵[1] 魏群义[1] 

机构地区：[1]重庆大学材料科学与工程学院,重庆400044 [2]重庆大学国家镁合金材料工程技术研究中心,重庆400044

出　　处：《重庆大学学报（自然科学版）》2013年第12期103-110,共8页Journal of Chongqing University

基　　金：国家973计划资助项目(2007CB613702)

摘　　要：采用SEM、EDS、XRD、TEM和力学性能测试等手段研究了挤压态Mg-9Li-3Al-xSr(LA93-xSr,x=0,1.5,2.5,3.5wt%)镁合金的微观组织与力学性能,探讨了Sr含量对挤压态合金的微观组织及力学性能的影响规律。结果表明:LA93-xSr镁合金包括α-Mg(hcp)和β-Li(bcc)两种基体相。Sr含量对挤压态合金的晶粒大小没有明显影响。随着Sr元素的加入,合金中形成Al4Sr新相,主要分布于α/β相界面,并沿挤压轴向呈流线分布。合金的强度随着Sr含量的增加呈现先增加后降低的趋势,合金的延伸率随着Sr含量的增加呈现逐渐降低的趋势。当Sr含量为2.5wt%时,挤压态Mg-9Li-3Al-2.5Sr(LAJ932)合金的抗拉强度达到最大值235.2MPa,屈服强度达到220.6MPa,延伸率为19.4%,合金呈现出良好的力学性能。挤压过程中,α-Mg相中发生形变诱发的晶粒细化,β-Li相中发生常规动态再结晶。The microstructure and mechanical properties of extruded Mg-9Li-3Al-xSr （LA93-xSr, x=0, 1. 5, 2.5, 3.5 wt%） alloys are investigated by SEM, EDS, XRD, TEM and mechanical property test. The influence of Sr content on microstructure and mechanical properties the extruded alloys is discussed. The results show that LA93-xSr alloys contain both a-Mg （hcp） and β-Li （bec） matrix phases. The effect of Sr on the grain size of the extruded alloys is not significant. The addition of Sr leads to the formation of intermetallic compound （Al4Sr）, which is mainly distributed along the α/β interface and appears fibrous structure along the extrusion direction. The mechanical properties of alloys initially enhance and then decrease while the elongation declines with the increase of Sr content. When Sr addition is 2.5wt%, the extruded Mg-gLi-3A1-2.5Sr （LAJ932） alloy exhibits a favorable combination of strength and ductility with an ultimate tensile strength of 235. 2 MPa, yield strength of 220. 6 MPa and an elongation of 19. 4%. Mierostructure evolution during extrusion is governed by deformation induced grain refinement in the a-Mg phase whereas dynamic recrystallization occurs in the β-Li phase.

关 键 词：镁锂合金 锶 挤压 微观组织 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]