Metastable-Stable Phase Transformation Behavior of Al2O3 Scale Formed on Fe-Ni-Al Alloys

作者：Hayashi Shigenari^*; Takada Yuto; Yoneda Suzue; Ukai Shigeharu

来源：Oxidation of Metals, 2016, 86(1-2): 151-164.

DOI：10.1007/s11085-016-9628-x

• Phase transformation of Al2O3
• Fe effect
• Synchrotron
• In-situ XRD

The oxidation behavior of Ni-Fe-41.5at.%Al alloys with different Fe/Ni ratios was investigated in air at 1000 A degrees C in order to clarify the effect of Fe on the phase transformation of Al2O3 scale, using in-situ high-temperature X-ray diffraction by means of synchrotron radiation. The oxidation mass gain of alloys after 25 h of oxidation generally decreased with increasing Fe content; however, the initial oxidation mass gain was significantly decreased by increasing alloy Fe content. In-situ X-ray diffraction analysis indicated that higher alloy Fe contents promoted rapid formation of the stable alpha-Al2O3, while lower Fe in the alloy maintained the metastable Al2O3 for longer time oxidation. The effect of Fe on promoting alpha-Al2O3 formation can be explained by the initial formation of alpha-Fe2O3, whose structure is isomorphous with alpha-Al2O3. The additional effect of Fe on the growth rate of alpha-Al2O3 is also discussed.

• 出版日期2016-8