金属型铸造Mg-Zn-Sn合金的非平衡组织及力学性能

Non-equilibrium Structure and Mechanical Properties of Permanent Mold Casting Mg-Zn-Sn Alloys

采用金属型铸造了Zn、Sn不同质量分数但总量为10%的Mg-xZn-(10-x)Sn合金,研究了其铸态组织特别是非平衡共晶组织及合金的力学性能。结果表明,Mg-Zn-Sn合金铸态组织为α-Mg、MgZn及(或)Mg2Sn相组成。Mg-9Zn-Sn和Mg-Zn-9Sn合金均产生了层片状共晶相,Mg-5Zn-5Sn合金中的共晶β相(MgZn和Mg2Sn)呈小块状均匀分布在晶界上,且基本上均为离异型共晶。采用夏尔公式计算出合金的非平衡共晶体积分数,Mg-9Zn-Sn合金中的共晶分数最高达14%,共晶组织几乎都呈现片状结构。力学性能试验结果表明,Mg-5Zn-5Sn合金具有最好的综合力学性能。此外,根据Zn、Sn原子在Mg中的固溶量的测试结果,进一步分析了合金的强韧性。

Mg-Zn-Sn alloys with different contents of Zn and Sn at a total amount of 10% were prepared by metal molds,and the as-cast structure,especially the non-equilibrium eutectic structure and the mechanical properties of the alloys were investigated.The results show that the as-cast structure of Mg-Zn-Sn alloys is composed ofα-Mg,MgZn and(or)Mg2Sn.Lamellar eutectic phases can be generated in the Mg-Zn-9Sn with high Sn content and Mg-9Zn-Sn alloys with high Zn content.The eutecticβphases(MgZn and Mg2Sn)in Mg-5Zn-5Sn alloys with the same content of Zn and Sn are uniformly distributed in the grain boundary in form of small blocks and the morphology of the eutectic phases is presented almost all divorced structures.The volume fraction of the non-equilibrium eutectic was calculated by the Schiel equation.The eutectic fraction of Mg-9Zn-Sn alloys with 9% Zn content is as high as 14%,and the eutectic structure almost all presents a lamellar structure.The experimental results of mechanical properties show that the Mg-5Zn-5Sn alloys has the desirable comprehensive mechanical properties.In addition,according to the test results of the solid solution amount of Zn and Sn atoms in magnesium matrix,the strength and toughness of alloys were further analyzed.