稀土Y对挤压态Mg-5Li合金组织及性能的影响

采用表面覆盖剂及氩气保护的熔炼方法制备了Mg-5Li-x Y(x=0,1,2,3,4)合金,研究了稀土元素Y对挤压态Mg-5Li合金的显微组织及力学性能的影响.研究结果表明,Mg-5Li合金中的Y元素主要是以稀土化合物Mg24Y5的形式存在于合金中;挤压变形后,合金发生了明显的动态再结晶,出现了大量的等轴晶,弥散分布的Mg24Y5相阻碍了动态再结晶过程中的晶粒长大,晶粒明显细化.挤压态Mg-5Li-3Y合金获得了优异的力学性能,其抗拉强度和断裂伸长率分别达到了231.63 MPa和9.35%,合金断裂方式主要为韧性断裂.

Effects of Y on Microstructure and Properties of As-Extruded Mg-5Li Alloys

With the protection of surface covering agents and argon protection， the Mg-5Li-x Y(x=0， 1， 2， 3， 4) alloys were prepared by conventional casting methods. The effects of rare earth on microstructure and mechanical properties of the as-extruded alloys were investigated. The results showed that the RE compound Mg24Y5 generated after adding Y into the Mg-5Li alloy. The dynamic recrystallization arose during the hot extrusion process， leading to a large number of equiaxed grains appeared. The dispersive distribution of Mg24Y5 phase hindered the growth of the grains during the dynamic recrystallization， which led to the grain refinement. The as-extruded Mg-5Li-3Y alloy achieved the best mechanical property: the tensile strength and elongation reached up to 231.63MPa and 9.35%， respectively. The fracture mode of the alloy is mainly ductile fracture.