研究了锑合金化对镁铝合金Mg-9Al-0.8Zn(AZ91)显微组织和力学性能的影响。结果表明，锑低合金化可以显著提高AZ91合金在从室温至200℃区间内的拉伸屈服强度。用扫描电镜和透射电镜详细分析了试样形变前后的显微组织及其变化，发现在AZ91合金中加入0.1wt%～1.0wt%的Sb后，合金的显微组织得到明显细化。Sb在AZ91合金中的存在方式主要有两种：(1)固溶入β-Mg17Al12相；(2)以Mg3Sb2形式析出，该颗粒相具有六方结构(D52型)，有很高的热稳定性，可以作为α-Mg非自发形核的衬底。在此基础上探讨了Sb合金化提高镁铝合金性能的机理：室温下主要是细化基体晶粒产生的晶界强化机制; 高温下则主要通过自生相(Mg3Sb2)粒子的弥散强化机制。%Small amount (0.4wt%-0.7wt%) of Sb addition to the Mg-Al based alloy AZ91(Mg-9Al-0.8Zn) resulted in significant increase in the yield strength at both ambient and elevated temperatures up to 200℃, By using SEM and TEM the change of microstructure of specimens before and after deformation was investigated in detail and the results indicated that the microstructure was fined effectively by the Sb addition. Sb in AZ91 exists in two forms:(1)precipitated in form of Mg3Sb2 particle with hexagonal structure(D52 type); (2) soluted in β-Mg17Al12 phase. Metallographic observation and theory calculation showed that the primary α-Mg could nucleated on Mg3Sb2 particle surface. The reason of improved mechanical properties by Sb was discussed: The RT strengthening mechanism of alloys containing Sb was fine grain strengthening resulted from dispersoids(Mg3Sb2) fining the matrix grain and the improvement of mechanical properties at elevated temperatures mainly resulted from the dispersion strengthening of Mg3Sb2 dispersoids.
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