【摘要】 为了研究Sb变质的Al-13Si-0.4Mg合金中共晶组织的不均匀性,采用液淬技术及光学显微镜考察Sb变质的Al-13Si-0.4Mg合金凝固过程中的组织形成过程。结果发现,在共晶反应初期,先期形成的共晶团的分枝很少,此时形成的共晶组织往往较粗大,表现为共晶Si片较厚、片间距大、分枝少;而此后的共晶反应过程中,共晶团的分枝增加,形成的共晶组织较细小,表现为共晶Si片较薄、片间距小、分枝密集。组织不均匀性的主要原因是Sb在共晶固/液界面前沿的富集程度不同,导致了Sb在共晶Si表面的吸附数量不同,从而影响了共晶Si的生长速度。更多还原

【Abstract】 Microstructure evolution of Sr modified Al-13Si-0.4Mg alloy during solidification process was observed by quenching and OM(optical microscope) to understand the un-uniformity of eutectic structure in the alloy.The results show that,during the initial stage of eutectic reaction,coarse eutectic structure is created in the alloy as a result of low branches in formed eutectic colony,characterized by thick eutectic Si flakes with wide lamellar spacing and a few branches.With advancing in reaction,eutectic grain is gradually refined due to the increase of branches in eutectic colony,characterized by thin eutectic Si flakes with narrow lamellar spacing and a lot of branches.Different enrichment of Sb at eutectic solid-liquid solidification front results in the different absorption coefficient of Sb on surface of eutectic Si,affecting the growth velocity of eutectic Si,which is responsible for the un-uniformity of structure in the alloy.更多还原