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Al-Si二元共晶反应发生在凝固后期,共晶(团)晶粒的形核、生长都直接影响缩松、热裂等缺陷的形成、杂质元素及化合物的分布等。对AlSi10.5亚共晶合金进行Sr变质,对未变质与变质合金进行微观组织观察和EBSD分析,并对未变质合金进行热分析。结果表明:无论变质与否,共晶在初生枝晶上形核和在枝晶间异质上形核的这两种情况都存在,并且Sr对初生α-Al有明显的变质效果,富Fe相可能对共晶Si相形核有较大影响。
The Al-Si binary eutectic reaction occurs in the late solidification stage. The nucleation and growth of eutectic (cluster) grains directly affect the formation of defects such as shrinkage and thermal cracking, and the distribution of impurity elements and compounds. Sr-modification of AlSi10.5 hypoeutectic alloy was carried out, microstructure observation and EBSD analysis of unmodified and deteriorated alloy were carried out, and thermal analysis of unmodified alloy was carried out. The results show that both the nucleation on the primary dendrites and the heterogeneous nucleation on the dendrites exist regardless of metamorphism or not, and Sr has a significant metamorphism effect on the primary α-Al. Fe The phase may have a greater impact on eutectic Si phase nucleation.