Mn对Mg-2Sn镁合金显微组织和力学性能的影响

Effects of Mn on Microstructure and Mechanical Properties of Mg-2Sn Magnesium Alloys

研究微量Mn元素对Mg-2Sn铸态和挤压态合金力学性能提升机制。采用铸造和热挤压方法将质量分数为0.3%、0.5%和1.0%的Mn元素添加到Mg-2Sn镁合金中,分别获得铸态和挤压态两种合金。采用电子万能材料试验机研究其力学性能;利用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)和电子背散射衍射(EBSD)研究其微观组织变化规律。随着Mn含量从0.3%增加到1.0%,铸态合金中第二相由Mg 2 Sn相向Mg 2 Sn与α-Mn相共存转变。第二相的转变使得铸态合金屈服强度和抗拉强度显著提升,延伸率变化不大,其中当Mn含量为0.5%时,其综合性能最佳,抗拉强度为210.3 MPa,屈服强度为117.5 MPa,延伸率为12.2%。挤压态合金随着Mn含量的增加,合金抗拉强度和屈服强度均增加,但延伸率降低,这可能与高Mn含量的合金形成较高的位错有关,其中挤压态Mg-2Sn-0.5Mn合金具有最佳的综合力学性能,抗拉强度为240.4 MPa,屈服强度为186.4 MPa,延伸率为13.1%。微量Mn元素可显著提升铸态和挤压态合金的抗拉强度和屈服强度,其中Mg-2Sn-0.5Mn合金综合力学性能最优。

We researched on the mechanism of trace Mn improving the mechanical properties of Mg-2Sn as-cast and extruded alloys.By using casting and hot extrusion methods,we added 0.3%,0.5%and 1.0%Mn to Mg-2Sn magnesium alloy,two kinds of alloy,namely as cast and extruded,were obtained.The mechanical properties were studied by electronic universal material testing machine.The microstructures were studied by optical microscope(OM),scanning electron microscope(SEM)and X-ray diffraction(XRD)and electron backscatter diffraction(EBSD).As the Mn content increased from 0.3%to 1.0%,the second phase in the cast alloy shifted from Mg 2 Sn phase to Mg 2 Sn phase andα-Mn coexist transformation.The transformation of the second phase significantly improved the yield and tensile strength of the cast alloy with little change in elongation.When the Mn content was 0.5%,its comprehensive performance was the best with a tensile strength of 210.3 MPa,a yield strength of 117.5 MPa,and an elongation of 12.2%.The strength of the extruded alloy increased with the increase of Mn content,while the elongation showed an opposite trend.This may be related to the formation of higher dislocations in alloys with high Mn content,the extruded Mg-2Sn-0.5Mn alloy had the best comprehensive mechanical properties with a tensile strength of 240.4 MPa,a yield strength of 186.4 MPa,and an elongation of 13.1%.Trace Mn could significantly improve the tensile and yield strength of cast and extruded alloys,and the comprehensive performance of Mg-2Sn-0.5Mn was the best.