挤压温度对Mg-6Zn-1Mn-4Sn-0.5Y镁合金组织和性能的影响

Effect of extrusion temperatures on microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn-0.5Y alloy

摘要:

通过光学显微镜（OM），X 射线衍射（XRD），扫描电子显微镜（SEM），电子背散射衍射（EBSD）以及拉伸试验对360和420℃挤压的Mg-6Zn-1Mn-4Sn-0.5Y变形镁合金的组织和性能进行了研究。研究结果表明，合金铸态和时效态的相组成为α-Mg, Mn, Mg7Zn3, Mg2Sn, 和 MgSnY相。挤压温度从360℃增加到420℃，动态再结晶完成，晶粒长大，合金的屈服强度，抗拉强度以及延伸率分别由259MPa, 350MPa 和 18.3% 降低至 239MPa, 332MPa和12.5%。理论计算和拉伸试验结果表明，细晶强化和固溶强化对合金屈服强度的增加产生决定性影响。

Abstract:

The microstructural evolution and mechanical properties of Mg-6Zn-1Mn-4Sn-0.5Y wrought alloy extruded at 360 and 420℃ were investigated by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron back scattered diffraction (EBSD) and tensile test. The results shown that the phase compositions of as-cast and extruded alloys were α-Mg, Mn, Mg7Zn3, Mg2Sn, and MgSnY phases. As the extrusion temperature increased from 360 to 420℃, dynamic recrystallization completed and grain growth occurred. The yield strength, ultimate tensile strength and elongation decreased from 259MPa, 350MPa and 18.3% to 239MPa, 332MPa and 12.5%, respectively. The theoretical values combined with the experimental values revealed that grain size strengthening and solid solution strengthening played the dominating role in the enhancement of yield strength.