热处理及Mn元素对汽车发动机用过共晶铝硅合金组织的影响

Influence of Heat Treatment and Element Mn on Microstructure of Al-Si Hypereutectic Alloy for Automotive Engines

针对传统铸造法加工过共晶铝硅合金组织粗大,合金性能恶化的问题,研究了热处理和元素Mn对过共晶铝硅合金中粗大富铁相的细化作用。研究表明：过共晶铝硅合金Al-16Si-2Fe经T6热处理工艺后,共晶硅形貌从短针状变为粒状,粗大针状富铁相β-Al_5Fe Si形貌未发生变化,热处理无法达到细化富铁相的目的 。元素Mn对共晶铝硅合金Al-16Si-2Fe中富铁相形貌改善明显,可使粗大富铁相β-Al_5Fe Si转化为细小颗粒状和枝晶状的Al_（15）（Fe Mn）_3Si_2相。当Mn含量为2wt%时,Al-16Si-2Fe合金中富铁相细化效果最佳。

The A1-Si hypereutectic alloy made by the traditional casting process has the problem of coarse microstructureand low performance. The refining effects of heat treatment and element Mn on the coarseiron-rich phase in A1-Sihypereutectic alloy were studied. The research result shows that after T6 heat treatment of AI-16Si-2Fe A1-Si hypereutecticalloy, the eutectic silicon morphology transforms from short needle into granular, the rough acicular 13-AlsFeSi iron-rich phasedoes not change. The heat treatment cannot achieve the goal of refining iron-rich phase. The morphology of rich-iron phaseinAI-16Si-2Fe hypereutectic alloy is improved by Mn, and the rough iron-rich phase 13-AlsFeSi transforms to small granular anddendritic Alls（FeMn）sSi2 phase. When the Mn content is 2wt%, the refinement of iron-rich phase in AI-16Si-2Fe alloy is best.