High temperature oxidation of Ni–19Fe–19Cr–5Nb alloys (based on the chemical composition of Alloy718) with different Al contents were investigated to elucidate the effect of Al on oxidation kinetics and scale formation during exposure at 800 °C in air. The experimental results indicated that the oxidation kinetics decreased with increasing Al content. The beneficial effect of Al could be attributed to be a result of the formation of γ′-Ni₃Al, which stabilizes γ′′-Ni₃(Nb,Al) and kinetically prohibits the coarsening of γ′′-Ni₃(Nb,Al) phases. Faster dissolution of finer γ′′-Ni₃(Nb,Al) precipitates due to greater γ-matrix / γ′′-Ni₃(Nb,Al) interface region in as-received Al-containing alloys could supply greater Nb flux for the formation of CrNbO₄, which promotes the formation of an exclusive Cr₂O₃ scale at the initial stage of oxidation.

研究了不同 Al 含量的 Ni-19Fe-19Cr-5Nb 合金（基于 Alloy718 的化学成分）的高温氧化，以阐明 Al 在 800 °C 空气中暴露期间对氧化动力学和氧化皮形成的影响。实验结果表明，氧化动力学随着Al含量的增加而降低。Al的有益效果可归因于形成γ'-Ni ₃ Al，其稳定γ''-Ni _{3 (Nb,Al)并在动力学上抑制γ''-Ni 3} (Nb ,Al)的粗化,Al)相。由于含铝合金中较大的 γ 基体 / γ''-Ni _{3 (Nb,Al) 界面区域，较细的 γ''-Ni 3} (Nb,Al) 析出物更快溶解，可以提供更大的 Nb 通量CrNbO ₄的形成，促进了氧化初期独有的Cr ₂ O ₃氧化皮的形成。