金属型铸造条件下Sb元素对ZL114A合金共晶Si和拉伸性能的影响

ZL114A合金是我国自主研发的铸造亚共晶Al-Si合金,变质共晶Si是提高其室温综合拉伸性能的重要方法之一。利用室温拉伸试验、扫描电镜观察研究了Sb元素对金属型铸造条件下ZL114A合金铸态和热处理态组织以及性能的影响。结果表明,对于铸态的ZL114A合金,Sb的加入将共晶Si由板片状变质为纤维状或颗粒状;经过热处理的ZL114A合金,Sb的加入使共晶Si的长径比变小,球化程度更高。在金属型铸造条件下,Sb元素能够提高ZL114A合金铸态和热处理态的室温综合拉伸性能,热处理后添加Sb的合金的抗拉强度和伸长率远远高于我国航空标准所要求达到的值。综合考虑ZL114A合金铸态和热处理态的共晶Si相形貌以及室温拉伸性能,Sb元素的最佳含量(质量分数)为0.09%。

Effect of Sb on eutectic Si and tensile properties of permanent mold cast ZL114 A alloy

ZL114A alloy is a hypoeutectic Al-Si casting alloy independently developed in China, with eutectic Si modification being one of the most important methods to improve its comprehensive tensile properties at room temperature. Effect of Sb on microstructure and properties of the as-cast and heat-treated ZL114A alloy was studied by tensile test at room temperature and SEM observation. The results show that for the as-cast ZL114A alloy, the addition of Sb modifies the eutectic Si from plate-like to fibrous or granular. For the heat-treated ZL114A alloy, the addition of Sb makes the aspect ratio of eutectic Si smaller and the degree of spheroidization higher. The Sb addition can improve the comprehensive tensile properties of the ZL114A alloy at room temperature under the condition of permanent mold casting, the tensile strength and elongation of the ZL114A alloy with Sb addition after heat treatment are much higher than those required in the aviation standard of China. Comprehensive consideration of the morphologies of eutectic Si and the tensile properties at room temperature of the as-cast and heat-treated ZL114A alloy shows that, the optimal content of Sb is 0.09% (mass fraction).