超轻Mg-Li-Al-Zn变型合金的组织及力学性能(英文)

Microstructure and Mechanical Properties of Superlight Mg-Li-Al-Zn Wrought Alloy

采用光学显微镜,SEM扫描电镜,XRD以及力学性能测试等手段,对比研究了Mg-7Li-3Zn,Mg-7Li-3Al和Mg-7Li-1.5Al-1.5Zn的合金组织,力学性能以及断裂机制。结果表明:Zn和Al主要以固溶形式存在于Mg-Li合金中,但仍有少量Al与Mg会形成中间相以颗粒状弥散分布在α-Mg的晶界处和β-Li的基体中。三类合金经过挤压变形后,组织得到细化,回复再结晶现象明显,力学性能发生明显改善。其中Mg-7Li-3Al的抗拉强度和最大延伸率达到最高,分别为239 MPa和27%,比铸态下分别提高34%和93%。

Superlight alloys, including Mg-7Li-3Zn, Mg-7Li-3A1 and Mg-7Li-1.5Al-1.5Zn, were prepared using a resistance furnace under the protection of argon atmosphere. The microstructures and phases of the alloys were studied by optical microscopy, scanning electronic microscopy （SEM）, X-ray diffraction （XRD）. The mechanical properties of these alloys were measured by a tensile tester. The results show that the Zn and A1 added in Mg-Li alloy mainly dissolve in a-Mg phase and β-Li phase. However, there still exists a part of the AI and Mg compound such as Mg17Al12 which is mainly distributed discontinuously at a phase boundary while the most of them in the fl phase are granular. The as-extruded Mg-7Li-3A1 alloy has the maximum tensile strength and yield strength of 239 MPa （34% higher than the as-cast） and 178 MPa （31% higher than the as-cast）, respectively, and the maximum elongation reaches to 27% （93% higher than the as-cast）.