热处理对往复挤压Mg-Sn-Al-Zn-Si合金组织与性能的影响

Effect of heat treatment on microstructure and properties of reciprocating extrusion Mg-Sn-Al-Zn-Si magnesium alloy

分析了固溶（T4）、时效（T5）及固溶＋时效双重处理（T6）对3种不同Sn含量的往复挤压Mg-Sn-Al-Zn-Si合金组织与性能的影响。结果表明：经过T4处理后,化合物相溶入基体相形成过饱和固溶体,合金强度大幅度下降,硬度和伸长率略有减小。经过T5处理后,合金强度和硬度均得到明显提高,其中规定塑性延伸强度改善幅度较大。经过T6处理后,组织中分布着大量弥散质点,合金强度和硬度改善效果显著,其中抗拉强度和硬度均高于T4和T5处理。随着Sn含量的增加,3种合金强度和伸长率均先升高后降低,而硬度单调升高。经过T5或T6处理后,伸长率呈现明显下降趋势,而合金硬度得到大幅度提高。生产实际中,对于规定塑性延伸强度要求较高的合金,采用T5热处理为宜;如果对合金硬度和抗拉强度要求较高,建议采用T6热处理。

The effects of solution treatment（ T4）,aging treatment（ T5） and solution plus aging treatment（ T6） on microstructure and property of the reciprocating extrusion Mg-Sn-Al-Zn-Si alloys with 3 different Sn content were analyzed. The results indicate that the compound phases dissolve into the matrix phase to form supersaturated solid solution after T4 treatment,the alloy strength decreases significantly and the hardness as well as elongation decreases slightly. After T5 treatment,the strength and hardness are improved prominently,especially the specified plastic elongation strength. After T6 treatment,the microstructure of the alloy consists of plenty of dispersed particles and enhanced the strength and hardness markedly,with both the ultimate strength and hardness being higher than that of T4 and T5 treatment. With the increase of Sn content,the strength and elongation of the alloy increase at first and then decrease,while the hardness increases monotonously. After T5 or T6 treatment,the elongation reduces significantly and the hardness of the alloy improves greatly. In practice,T5 is suggested for higher specified plastic elongation strength,while T6 for higher hardness and tensile strength.