Microstructure evolution and phase transformation of traditional cast and spray-formed hypereutectic aluminium-silicon alloys induced by heat treatment

Long-gang Hou1),Yuan-hua Cai1),Hua Cui2),and Ji-shan Zhang1) 1) State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China 2) School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China

摘 要：Microstructural evolution and phase transformation induced by different heat treatments of the hypereutectic aluminium-silicon alloy,Al-25Si-5Fe-3Cu（wt%,signed as 3C）,fabricated by traditional cast（TC） and spray forming（SF） processes,were investigated by differential scanning calorimetry（DSC） and scanning electron microscopy（SEM） combined with energy dispersive X-ray spectroscopy and X-ray diffraction techniques.The results show that Al7Cu2Fe phase can be formed and transformed in TC-and SF-3C alloys between 802-813 K and 800-815 K,respectively.The transformation from β-Al5FeSi to δ-Al4FeSi2 phase via peritectic reaction can occur at around 858-870 K and 876-890 K in TC-and SF-3C alloys,respectively.The starting precipitation temperature of δ-Al4FeSi2 phase as the dominant Fe-bearing phase in the TC-3C alloy is 997 K and the exothermic peak about the peritectic transformation of δ-Al4FeSi2→β-Al5FeSi is not detected in the present DSC experiments.Also,the mechanisms of the microstructural evolution and phase transformation are discussed.

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