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系统研究了微量Ca的加入对Mg-12Zn-4Al-0.3Mn合金显微组织和高温抗蠕度性能的影响。结果表明,Mg-12Zn-4Al-0.3Mn铸造镁合金的显微组织主要由α-Mg基体和块状准晶晶界相组成,在成分上准晶相与三元平衡相图中τ相(Mg32(Al,Zn)49)接近。少量Ca加入母合金后,块状准晶相部分转变为τ相和层片状φ相(Al2Mg5Zn2)。随Ca加入量增加,φ相的体积分数增多。Ca的加入显著提高了合金高温抗蠕变性能,175℃,70MPa蠕变条件下,Ca加入量为0.6%时,合金呈现最好的蠕变抗力,其稳态蠕变速率比母合金下降了近一个数量级。
The effect of adding trace amount of Ca on microstructure and high temperature creep resistance of Mg-12Zn-4Al-0.3Mn alloy was systematically investigated. The results show that the microstructure of Mg-12Zn-4Al-0.3Mn cast magnesium alloy consists mainly of α-Mg matrix and bulk quasi-crystalline grain boundary phase. The composition of the quasi- Mg32 (Al, Zn) 49). After a small amount of Ca is added to the mother alloy, the bulk quasicrystalline phase is partially transformed into a τ phase and a lamellar phase φ (Al2Mg5Zn2). With the increase of Ca addition, the volume fraction of φ phase increased. The addition of Ca significantly improves the creep resistance of the alloy at high temperature. When the amount of Ca added is 0.6% at 175 ℃ and 70MPa, the alloy exhibits the best creep resistance and the steady creep rate is lower than that of the parent alloy Nearly an order of magnitude.