不同相组成Mg-Li二元合金的力学性能及阻尼性能

Mechanical properties and damping capacity of Mg-Li alloys with different phases

在氩气保护下采用电磁感应真空熔炼制备出单一α-Mg相、单一β-Li相及两相共存的3种不同相态的Mg-Li二元合金,并运用光学显微镜、XRD、阻尼测试及力学测试方法对合金的组织结构、力学性能及阻尼性能进行分析和讨论。结果表明:Li含量的增加使合金的相态发生改变,同时对合金起到晶粒细化的作用,且能有效地提高合金的屈服强度。体心立方结构的β-Li相会增大合金的临界应变振幅以及阻尼性能,但两相共存状态的Mg-Li合金具有最好的抗拉强度及伸长率。Mg-Li二元合金的新阻尼机制是由低温区域位错滑移、高温区域的晶界滑移以及合金中的晶格畸变这3种阻尼机制叠加而成。

The vacuum induction melting furnace was used to melt the Mg-Li alloys under the protection of argon atmosphere. Three kinds of Mg-Li binary alloys, singleα-Mg phase alloy, singleβ-Li phase alloy and the dual-phase alloy are obtained. The optical microscope （OM）, X-ray diffractometer （XRD）, scanning electron microscope （SEM）, tensile properties test, amplitude-damping test and temperature-damping test were used to analyze the mechanical properties and the damping capacity of Mg-Li alloys with different phases were studied. The results show that the increase of Li content changes the phases of the alloy, and also plays an important role in the grain refinement which can effectively improve the yield strength. The BCC-structuredβ-Li phase improves the critical stain amplitude and the damping capacity of Mg-Li alloys, and the dual-phase Mg-Li alloy has the best tensile strength and elongation. The new damping mechanism of Mg-Li alloy is superposed by the dislocation gliding at low temperature, grain boundary sliding at high temperature and the lattice distortion.