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采用金属型铸造法,制备Sr含量0~1.2%(质量分数)的AZ31-xSr系列镁合金试样。采用OM、SEM、EDS、力学性能测试等方法研究其显微组织和力学性能,并结合DSC研究合金铸态组织的细化机制。结果表明:加入0.3%的Sr时,合金的显微组织得到了明显细化并有少量的Al4Sr生成,当Sr的含量进一步增加时,合金中的Al4Sr含量增加并呈粒状和杆状分布且使β-Mg17Al12弥散均匀分布;当Sr的含量为1.2%时,合金的晶界由连续网状的Al4Sr构成,并有少量的Mg-Al-Sr三元相生成。合金的常温力学性能在Sr含量为0.9%时达到最优,抗拉强度和延伸率分别为194MPa和7.6%,分别比AZ31提高了27.6%和36.8%。
AZ31-xSr series magnesium alloy samples with Sr content of 0-1.2% (mass fraction) were prepared by metal casting method. The microstructure and mechanical properties of the as-cast alloy were studied by OM, SEM, EDS, mechanical properties testing and DSC. The results show that when adding 0.3% Sr, the microstructure of the alloy is obviously refined and a small amount of Al4Sr is formed. When the content of Sr is further increased, the content of Al4Sr in the alloy increases and becomes granular and rod- β-Mg17Al12 dispersed evenly distributed; when the content of Sr is 1.2%, the grain boundary of the alloy is composed of continuous reticular Al4Sr, and a small amount of Mg-Al-Sr ternary phase is formed. The room-temperature mechanical properties of the alloy reached its optimum when the content of Sr was 0.9%. The tensile strength and elongation were 194MPa and 7.6% respectively, which were 27.6% and 36.8% higher than that of AZ31 respectively.