Effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–Zn–Ca alloys

Hong-xiang Li，Shi-kai Qin，Ying-zhong Ma，Jian Wang，Yun-jin Liu，Ji-shan Zhang

State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing

摘 要：The effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–x Zn–0.2 Ca alloys（x = 0.6 wt%, 2.0 wt%, 2.5 wt%, hereafter denoted as 0.6 Zn, 2.0 Zn, and 2.5 Zn alloys, respectively） are investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstructure of the 0.6 Zn alloy is composed of α-Mg, Mg2 Ca, and Ca2 Mg6 Zn3 phases, whereas 2.0 Zn and 2.5 Zn alloys only contain α-Mg and Ca2 Mg6 Zn3 phases, as revealed by X-ray diffraction（XRD） and transmission electron microscopy（TEM） analyses. Moreover, with increasing Zn content, both the ultimate tensile strength（UTS） and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS（178 MPa） and the highest elongation to fracture（6.5%） are obtained for the 2.0 Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides an updated investigation of the alloy composition–microstructure–property relationships of different Zn-containing Mg–Zn–Ca alloys.

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