蒸着アルミニウムめっき Fe-Cr-Al 合金箔上に形成したアルミナ皮膜の相転移

概要

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The phase transformation of Al_2O_3 formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-20Cr-5Al alloy foil of the similar composition, and their oxidation kinetics have been studied in air at 1073-1373K using XRD, SEM and SIMS. It was found that the deposition of Al promotes the growth of metastable aluminas. The transformation of metastable Al_2O_3 to α-Al_2O_3 formed on the Al-deposited foil is slower than that on the alloy foil. The values of kp for the growth of α-Al_2O_3 on the Al-deposited foil is smaller than that on the alloy foil in the temperature range 1273 to 1373K. These are attributable to the purity of the Al_2O_3 initially formed on Al-deposited foil. The phase transformation of Al_2O_3 is reflected by the scale morphology. The nucleation of θ-Al_2O_3 occurs on the surface of granular γ-Al_2O_3. θ-Al_2O_3 having a shape of whisker grows on the oxide surface. The morphology of whiskers is more round, after θ-Al_2O_3 transforms to α-Al_2O_3. We obtained the TTT diagrams for the phase transformation of Al_2O_3 scales formed on both foils in air in the temperature range 1073 to 1373K.
社団法人日本鉄鋼協会の論文
1997-03-01