固溶处理对铸态Mg-4.8Al-2.7Ca-0.4Mn合金组织及力学性能的影响

Effect of solution treatment on microstructure and mechanical properties of as-cast Mg-4.8Al-2.7Ca-0.4Mn alloy

采用光学显微镜、扫描电镜、X射线能谱仪、X射线衍射仪、硬度测试及拉伸性能测试等手段分别研究了铸态Mg-4.8Al-2.7Ca-0.4Mn合金固溶处理前后的组织演变及力学性能。结果表明,铸态Mg-4.8Al-2.7Ca-0.4Mn合金的微观组织中,α-Mg相呈现典型的枝晶形态,枝晶间分布着大量在凝固过程中形成的Al_(2)Ca相;固溶处理对第二相的形貌有显著影响,随着固溶时间的增加,枝晶偏析减弱,Al_(2)Ca相从网状分布演变为多边形或细块状;经500℃固溶4 h,合金具有较好的综合拉伸性能,抗拉强度、屈服强度及伸长率分别达到222.0 MPa、182.5 MPa和4.5%。

Microstructure evolution and mechanical properties of as-cast and solution treated Mg-4.8 Al-2.7 Ca-0.4 Mn alloy were investigated by means of optical microscope,scanning electron microscope,X-ray energy spectrometer,X-ray diffractometer,hardness test and tensile property test,respectively.The results show that theα-Mg phase in the microstructure of as-cast Mg-4.8 Al-2.7 Ca-0.4 Mn alloy presents typical dendrite morphology,and a large amount of Al_(2)Ca phases formed during solidification are distributed among dendrites.The solution treatment has a significant influence on the morphology of second phases.With the increase of solution treatment time,the dendrite segregation is weakened,and the Al_(2)Ca phase changes from reticular distribution to polygonal or fine blocky.The alloy solution treated at 500℃ for 4 h exhibits good comprehensive tensile properties,with the tensile strength of 222.0 MPa,the yield strength of 182.5 MPa,and the elongation of 4.5%.