Sn对ZM61合金组织与性能的影响

Effects of Sn on Microstructure and Mechanical Properties of ZM61 Alloy

摘要:

通过光学金相(OM)，扫描电镜(SEM)，X射线衍射(XRD)等分析方法，研究不同Sn含量对Mg-6Zn-1Mn(ZM61)合金显微组织和力学性能的影响，并初步探讨Sn元素在镁合金中的存在形式和作用机理。结果表明：Sn元素在ZM61合金中主要以Mg2Sn相存在；Sn元素不仅可以改善合金的铸造性能，所形成弥散的Mg2Sn相颗粒还可以明显的细化晶粒改善组织，提高合金的力学性能，其中经440 ℃, 2 h+90 ℃, 24 h+180 ℃, 8 h双级时效处理的ZM61-4Sn合金具有最佳的综合力学性能，其屈服强度、抗拉强度和延伸率分别为358 MPa、374 MPa和4.6%；Sn的加入不会改变合金的断裂机制，但是粗大的Mg2Sn粒子会成为裂纹源，从而降低合金的塑性，所以Sn含量不宜过高，不大于4%较为合适

Abstract:

The microstructure and mechanical properties of the ZM61 alloy (Mg-6Zn-1Mn) with different Sn content were researched by optical microscope (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and tensile tests. The existence form and acting mechanism of Sn element in ZM61 alloy and the influence of Sn content on microstructure and mechanical properties were investigated. The results show that the addition of Sn can improve the casting fluidity and the formation of the dispersed Mg2Sn particles can refine the MgZn phase to improve the microstructure and the mechanical properties of ZM61 alloy. The ZM61-4Sn alloy with double aging treatment has the best mechanical properties, with tensile strength of 374 MPa, yield strength of 358 MPa and elongation of 4.6%. However the addition of Sn cannot change the fracture behavior of ZM61 alloy while the coarse Mg2Sn phase can become crack source during fracture to decrease the plasticity. Therefore, Sn content should not be too high, no more than 4%.