采用剧塑性变形工艺(等通道转角挤压和轧制)以及随后的短时间退火制备高性能Mg-Li合金，通过显微组织观察、扫描电镜分析、X射线衍射仪测试和室温拉伸测试等研究变形前后合金组织、力学性能及强化机制。结果表明：合金铸态晶粒粗大，主相为β相，α相分布于β相的晶界以及晶内；同时，晶内存在大量Al 2 Y和AlLi析出相。由于动态回复作用显著，合金变形时并未发生明显的动态再结晶现象；经短时间退火后，合金组织发生完全再结晶，其晶粒细化至27.1μm(12pra工艺，即等通道转角挤压、轧制及退火)。铸态合金的抗拉强度和伸长率分别为131.1 MPa和47.1%；经12pr(等通道转角挤压及轧制)变形后，合金的伸长率达到90.5%，而抗拉强度稍有提高，这主要受位错协调变形及动态回复作用的影响；退火后合金的伸长率显著降低而强度提高至237.6 MPa (12pra)，出现退火致强化现象，其主要的机制是有限位错源强化及晶界强化。
The microstructure, mechanical properties and strengthening mechanism of Mg-Li alloys processed by severe plastic deformation (equal channel angular pressing (ECAP) and rolling) and subsequent annealing were analyzed by OM, SEM, XRD and tensile testing. The results show that the initial grains of the as-cast alloy are coarse andβphase the main position, while α phase distributes inside or in the boundary. Meanwhile, there are lots of precipitate phases Al2Y and AlLi in the grain. Obvious dynamic recrystallization (DRX) does not occur during the deformation due to the significant effect of dynamic recovery (DR). After a short time annealing, the alloy is completely recrystallized with grain size refined to 27.1μm (process of 12pra:ECAP, rolling and annealing). The tensile strength and elongation of the as-cast alloy are 131.1 MPa and 47.1%, respectively. After the process of 12pr (ECAP and rolling), the elongation of the alloy reaches 90.5%, while the tensile strength is improved slightly. This can be explained based on the effect of DR and dislocation-coordinated deformation. Subsequent annealing treatment results in an increase in tensile strength (12pra:237.6 MPa) and a significant decrease in elongation because of the dislocation source-limited hardening and grain boundary strengthening mechanism.
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