Mg-8Zn-1Ag-0.7Zr合金组织和力学性能研究

利用OM、SEM等手段对Mg-8Zn-1Ag-0.7Zr合金的微观组织、析出相成分和力学性能进行了研究,为工程应用提供参考。结果表明,Mg-8Zn-1Ag-0.7Zr合金以等轴晶方式凝固,铸态合金主要由α-Mg、Mg-Zn-Ag三元化合物和Zn2Zr3相组成,第二相主要集中分布在晶界上。热处理后,晶界上第二相的连续分布形态得到明显改善,Zn元素在基体中的含量变化明显。铸态时,Zn元素含量为3.09%,经固溶处理后,增加为8.24%。时效处理后,Zn元素含量下降至5.42%,起到很好的析出强化作用。T4态合金的抗拉强度、屈服强度和伸长率分别为311.4 MPa、147.4 MPa和13.7%,较铸态提高明显。经T6处理后,合金抗拉强度、屈服强度和伸长率为325.4 MPa、217.6 MPa和5.1%。

Microstructure and Mechanical Properties of Mg-8Zn-1Ag-0.7Zr Alloy

The microstructure and mechanical properties of Mg-8 Zn-1 Ag-0.7 Zr alloy were investigated by OM、SEM and tensile testing. The experimental results reveal that the Mg-8 Zn-1 Ag-0.7 Zr alloy is solidified in form of equiaxial crystal, and the as-cast alloy is mainly composed of the α-Mg、Mg-Zn-Ag ternary compound and Zn2Zr3 phase. The second phase is mainly distributed along the grain boundary. After heat treatment, distribution morphology of secondary phase is improved obviously on the grain boundary. Zn content in the matrix is changed greatly. After solid solution, Zn content in the alloy is increased from 3.09% in as-cast state to 8.24%, while it is decreased to 5.42% after aging treatment, presenting the satisfied precipitate strengthening effects. The tensile strength, yield strength and elongation of the alloy by T4 treatment reach 311.4 MPa, 147.4 MPa and 13.7%. After T6 treatment, the tensile strength, yield strength and elongation of the alloy reach 325.4 MPa, 217.6 MPa and 5.1%,respectively.