Abstract: A series of Mg-12Zn-4Al-0.3Mn (ZA124) based alloys with additions of calcium have been prepared and their microstructure and properties have been investigated. The results show that Mg-12Zn-4Al-0.3Mn alloy consists of the α-Mg matrix and block quasicrystal and exhibits excellent creep resistance compared to commonly used AZ91 alloy. A small amount of calcium addition to the ZA124 based alloys increased the yield strenghth at both ambient and elevated temperatures as well as creep resistance, although the ductility decreased slightly. Microanalysis indicated that the addition of calcium decreased the quasicrystalline phase and caused the formation of some lamellar precipitates of Al2Mg5Zn2 with orthorhombic crystal structure. This Ca-containing Al2Mg5Zn2 phase with high stability straddled the grain boundaries and strengthened grain boundaries by inhibiting crack propagation during creep tests at elevated temperature.

Key words: Mg-12Zn-4Al-0.3Mn (ZA124)| microstructure| mechanical strength| creep properties

摘要： A series of Mg-12Zn-4Al-0.3Mn (ZA124) based alloys with additions of calcium have been prepared and their microstructure and properties have been investigated. The results show that Mg-12Zn-4Al-0.3Mn alloy consists of the α-Mg matrix and block quasicrystal and exhibits excellent creep resistance compared to commonly used AZ91 alloy. A small amount of calcium addition to the ZA124 based alloys increased the yield strenghth at both ambient and elevated temperatures as well as creep resistance, although the ductility decreased slightly. Microanalysis indicated that the addition of calcium decreased the quasicrystalline phase and caused the formation of some lamellar precipitates of Al2Mg5Zn2 with orthorhombic crystal structure. This Ca-containing Al2Mg5Zn2 phase with high stability straddled the grain boundaries and strengthened grain boundaries by inhibiting crack propagation during creep tests at elevated temperature.

关键词: Mg-12Zn-4Al-0.3Mn (ZA124)| microstructure| mechanical strength| creep properties