ECAP制备Mg-2Si合金的组织与力学性能

Structure and mechanical properties of Mg-2Si alloy prepared by ECAP

实验研究了铸态Mg-2Si合金在挤压温度为623 K和挤压路径为Bc条件下,ECAP变形道次对Mg-2Si合金组织、力学性能的影响。结果表明:随着挤压道次增加,合金中的层片状和杆状的晶共Mg2Si相均得到细化且分布趋于均匀;ECAP变形对合金中粗大的块状初生Mg2Si相的细化作用较弱;8道次变形后合金组织中仍有大量粗大的初生Mg2Si相;4、8道次后,合金中形成了稳定的(0002)基面织构,变形道次越多,织构强度越高。与铸态相比,ECAP变形后合金的室温力学性能得到提高,在8道次后,合金的室温性能达到最大值,其屈服强度、抗拉强度和伸长率分别为125 N/mm2、232 N/mm2和20.2%。随着挤压道次的增加,晶粒尺寸减小,Mg2Si相得到细化,有利于提髙力学性能。随着挤压道次的增加,加工硬化值逐渐增加,有利于提升材料的力学性能。力学性能是由基体晶粒细化程度、第二相形貌及分布、基面织构共同作用的结果。

It is investigated in the experiment that how the deformation pass influences the structure and mechanical properties of as-cast Mg-2Si alloy extruded by ECAP with Be extrusion path at 623 K.The results show that the lamellar and rod-like Mg2Si eutectic phases in the alloy are refined and the distribution tends to be uniform with the increase of extrusion passes.The ECAP deformation has a weaker effect on the coarse bulk Mg2Si primary phase in the alloy.There are still a large amount of coarse Mg2Si primary phases in the alloy after 8 deformation passes.After 4 and 8 deformation passes,the stable(0002)base texture is formed in the alloy,and the texture strength increases with the increase of deformation passes.The mechanical properties at room temperature of the alloy after ECAP deformation are increased compared with those of the as-cast alloy.After 8 passes,the properties at room temperature of the alloy reach the maximum,among which yield strength,tensile strength and elongation are 125 N/mm2,232 N/mm2 and 20.2%,respectively.As the number of extrusion passes increases,the grain size decreases,the Mg2Si phase is refined,and the work hardening value increases,which is beneficial to improve mechanical properties.The mechanical properties are determined by the grain refinement,morphology and distribution of the second phase and the texture of the base.