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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℃,2h+90℃,24h+180℃,8h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358MPa、374MPa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。
The effects of different Sn contents on the microstructure and mechanical properties of Mg-6Zn-1Mn (ZM61) alloy were investigated by means of optical metallography (OM), scanning electron microscopy (SEM) and X-ray diffraction Presence and Mechanism of Sn Element in Magnesium Alloy. The results show that the Sn element mainly exists in the Mg2Sn phase in the ZM61 alloy. The Sn element can not only improve the casting performance of the alloy, but also improve the mechanical properties of the alloy by refining the grain size of Mg2Sn phase particles. The ZM61-4Sn alloy aged at 440 ℃, 2h + 90 ℃, 24h + 180 ℃, 8h has the best comprehensive mechanical properties, and the yield strength, tensile strength and elongation are 358MPa, 374MPa and 4.6% ; The addition of Sn will not change the fracture mechanism of the alloy, but coarse Mg2Sn particles will become the source of cracks, thereby reducing the plasticity of the alloy, so the Sn content should not be too high, not more than 4% is more appropriate.