ろう付用Al–Si系合金材を用いたポーラスアルミニウムの接合におけるポーラスアルミニウムの気孔構造変化と液相の挙動

抄録

In this study, an attempt was made to braze porous Al samples fabricated by powder metallurgy with an Al–2.5 mass%Si alloy brazing sheet at 863–883 K. These porous Al samples were fabricated by using 99.9% purity Al powder. During the brazing process, the porous Al was deformed. The deformation was greater at higher brazing temperatures, and which resulted in reduced porosity localized at near the interface between the porous Al and the brazing sheet. As determined by cross-sectional observation after brazing, the cell walls of the porous Al showed a different microstructure compared to that prior to brazing. Electron probe microanalysis revealed the presence of Si in the cell walls after brazing. These results indicate that the liquid phase, which was formed in the brazing sheet during brazing and contained Si, migrated to the cell walls. To clarify the migration behavior of the liquid phase on the surface and in the cell wall, a sintered bulk Al sample was brazed with an Al–2.5 mass%Si brazing sheet at 873 K. The results suggest that the liquid phase preferentially migrated both on the surface and through the powder boundaries.