熔体过热处理对Mg-5Si合金组织与性能的影响

Effect of Melt Superheating Treatment on Microstructure and Properties of Mg-5Si Alloy

采用质量分数为99.9%的纯镁锭和99.9%的粒度为45μm的硅粉,制备了质量分数为5%的Mg-5Si合金,研究了熔体过热温度和保温时间对Mg-5Si合金铸态组织和力学性能的影响。研究实现了Mg2Si相尺寸由处理前的27μm减小到20μm,此时初生Mg2Si相的平均尺寸最小,分布趋于均匀,形貌逐渐向树枝状转变,甚至溶解为较为圆整的颗粒,且共晶Mg2Si相层片间距较小,并采用抗拉强度、屈服强度和伸长率表征其力学性能。研究结果表明:熔体过热温度为770℃、保温时间为30min时,合金的抗拉强度、屈服强度和伸长率分别为152MPa、84MPa和6.5%,合金的力学性能得到明显改善。

The Mg-5Si alloy with 5%mass fraction was made by using a pure magnesium ingot with 99.9%mass fraction and silicon powder with 99.9%mass fraction which particle size is 45μm.The effects of melt superheating temperature and holding time on casting structure and mechanical properties of Mg-5Si alloy were studied.The size of Mg 2 Si is decreased from 27μm to 20μm and the average size of primary Mg 2 Si phase is the smallest.The morphology of primary Mg 2 Si phase gradually changes to dendrite,and even dissolves into some round particles with uniform distribution.The lamellar spacing of eutectic Mg 2 Si phase is small.Furthermore,the tensile strength,yield strength and elongation were employed to characterize the mechanical properties.The result shows that when the melt superheating temperature is 770℃and holding time is 30 min,the mechanical properties of alloy are improved obviously and the tensile strength,yield strength and elongation of the alloy are 152 MPa、84 MPa and 6.5%respectively.