NODULARIZATION OF α-AlFeSi COMPOUNDS IN PURE ALUMINUM

摘要

The aim of this research is to establish the mechanism of nodularization of α-AlFeSi constituents based on the hypothesis that this phase particles form in hydrogen bubbles during the solidification. In order to prove this hypothesis, the following experiments were done: 1) the observation of structure of α-AlFeSi nodules, 2) the effect of hydrogen bubbles on the formation of α-AlFeSi nodules. As a result, it became clear that the morphology of α-AlFeSi nodules, which forms during solidification is a spherical shape with a hollow shell. Therefore this structure indicates that α-AlFeSi particles nucleates on the inner wall of the hydrogen bubbles which evolve during solidification. Furthermore, the size and density of α-AlFeSi nodules changed with the cooling rate of solidification and their variations agreed with those of the hydrogen bubbles. Thus, this hypothesis that α-AlFeSi nodules form in hydrogen bubbles was proved.