アルミニウム基2元系合金溶湯による鉄の溶損における金属間化合物層の溶出メカニズム

抄録

  Erosion testing was conducted on iron specimens in various aluminum-based molten binary alloys, and the correspondence between the intermetallic compounds formed at the contact interface and the thermodynamically stable phases was examined. On the basis of the results, the mechanism and dominant factor of the dissolution of the intermetallic layers were investigated. Although the erosion ratio of the specimens by molten Al-3%Mn alloy was significantly small, the ratios by molten alloys of the Al-Si system were great, in comparison to those by other melts. Meanwhile, the intermetallic compounds identified by EBSD corresponded to the stable phases based on the equilibrium calculation of the compositions analyzed by EDS and/or the pseudo binary phase diagrams of the aluminum alloy-Fe systems. In addition, there was a positive correlation between the experimental erosion rate and apparent saturation solubility of Fe to the melts based on the pseudo binary phase diagrams. These results suggest that the dissolution of the layers was caused by almost the same mechanism as the phenomena described by Noyes-Whitney-Nernst equation, and that the saturation solubility of Fe is a dominant factor affecting the diffusion-controlled dissolution from the solid-liquid interfaces under local equilibrium.