Bi含量对Al-Mg2Si合金的微观组织及拉伸性能的影响

Effect of Bi Content on Microstructure and Tensile Properties of Al-14Mg2Si Alloy

针对国家能源集团煤炭企业的采煤设备部件偶合器力学性能较差的问题,利用金相、XRD和力学性能测试等方法研究了Bi含量对铸态Al-Mg2Si合金的微观组织及拉伸性能的影响。结果表明,合金元素Bi对合金中的初生和共晶Mg2Si均具有显著的变质效果。当Bi含量增加到0.3%时,初生Mg2Si的形貌从粗大尖角多边形变成平角多面体形状,平均粒径从43μm下降至24μm;同时,共晶Mg2Si相从迷宫状变为短纤维状或点状。当Bi含量超过0.5%时,共晶Mg2Si呈现出过变质现象。Bi可以提高合金的抗拉强度和伸长率;与未变质合金相比,添加0.5%Bi的合金抗拉强度和伸长率分别提高了34.9%和90.5%。

Aiming at the poor mechanical properties of coupler of coal mining equipment components in coal mining enterprises of national energy group,the influence of Bi content on microstructure and tensile properties of Al-14 Mg2 Si alloy was studied by means of metallography,XRD and mechanical property test.The results show that the alloy element Bi has significant deterioration effect on the primary and eutectic Mg2 Si in the alloy.When the Bi content increased to0.3%,the morphology of primary Mg2 Si changes from thick and sharp polygon to flat polyhedron,and the average particle size decreased from 43μm to 24μm.At the same time,the eutectic Mg2 Si phase changes from labyrinth to short fiber or dot.When Bi content exceeds 0.5%,eutectic Mg2 Si presents metamorphism.Bi can improve the tensile strength and elongation of the alloy.The tensile strength and elongation of the alloy with 0.5%Bi are increased by 34.9%and 90.5%,respectively,compared with that of the unspoiled alloy.