溶融 Zn-5mass%Al 合金浴におけるΓ・Fe-Zn 相の Al-Fe 金属間化合物への変化過程

概要

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Following the previous report, it has been investigated the changing process from Fe-Zn intermetallic compounds (IMCs) to Al-Fe IMCs in a molten Zn-5mass%Al alloy at 450℃. Γ・Fe-Zn phase changed directly to Zn-containing Al_5Fe_2 at an extremely high rate. Γ phase had a strong orientation of {110} plane parallel to the steel surface, but Zn-containing Al_5Fe_2 had not a significant orientation. And a special orientation relationship between Γ phase and Al_5Fe_2 could not be found. Combining these results with the previous results on the changing process from ζ・Fe-Zn phase (two steps reaction ; ζ・Fe-Zn phase⟶Al-Fe-Zn amorphous phase⟶Al_5Fe_2), it is considered that whether Fe-Zn IMCs change to Al_5Fe_2 by the direct reaction or the two steps reaction depends on the Fe atomic concentration of these IMCs. After the whole of Γ・Fe-Zn layer changed to Zn-containing Al_5Fe_2, Al_5Fe_2 layer peeled off the steel substrate. This is considered to be due to that a Zn-rich phase which had been formed like a chain in Zn-containing Al_5Fe_2 layer changed to voids by the outer diffusion of Zn in this phase. The Zn-rich phase is understood to be formed by the concentration of Zn discharged from Γ・Fe-Zn phase during changing to Zn-containing Al_5Fe_2.
社団法人日本鉄鋼協会の論文
1998-09-01