鐵鈷鎳基高熵合金氧化行為之研究

The Oxidation Behavior of FeCoNi-base High entropy Alloys in Dry Air

本研究探討FeCoNi、FeCoNiCuCr和FeCoNiCuAl三種鐵鈷鎳基高熵合金於800～1000℃ 空氣的氧化行為。研究結果顯示，三種合金的氧化動力學皆遵守拋物線型定律，且氧化速率隨溫度的上升而增加，其中以FeCoNiCuAl的抗氧化能力最佳。三種高熵合金氧化後在表面生成不同的氧化物，其中在FeCoNi合金外層以CoO為主，Fe2O3分佈在中央，內層則為CoNiO2，且由橫截面分析得知FeCoNi合金會形成FeO的內氧化粒子；FeCoNiCuCr合金外層主要生成CuO及少量Fe2O3內層則為FeCr2O4及CuCrO2、FeCoNiCuAl則是生成Al2O3為主，而生成Al2O3是含Al之合金氧化速率降低的主要原因。

The oxidation behavior of three FeCoNi-base high entropy alloys (HEA's) containing Fe-Co-Ni, Fe-Co-Ni-Cu-Cr, and Fe-Co-Ni-Cu-Al was studied over the temperature range 800~1000℃ in air. The results indicated that the oxidation kinetics of these alloys followed the parabolic rate law at all temperatures, and the oxidation rate constants increased with increasing temperature. The scales formed on the HEA's were strongly dependent on alloy composition, consisting of the outer-layer of most CoO, the middle-layer of Fe2O3, the inner-layer of CoNiO2 and the internaloxide particales of FeO for FeCoNi; of mostly CuO and minor Fe2O3 in the outer-layer, FeCr2O4 and CuCrO2 in the inner-layer for FeCoNiCuCr; and of mostly Al2O3 for FeCoNiCuAl. The formation of Al2O3 was responsible for the reduction of oxidation rates for the Al-containing HEA.