Selective oxidation is a common strategy for enhancing protective oxide layers on an alloy. In this work, oxide films were obtained on Al₂Au under a series of temperatures, and the structure, chemical state, and corrosion resistance were investigated. The oxidation behavior was confirmed to be temperature-dependent, exhibiting two distinct kinds of oxide films. Uniform oxidation occurred below the critical temperature T_s (700 < T_s < 800 °C), resulting in ultrathin oxide layers (<10 nm) with corrosion resistance enhanced by Au solute atoms. Phase-separate oxidation, occurring at temperatures above T_s, resulted in a much thicker oxide-affected region (250–300 nm) composed of Al₂O₃ and AlAu phases. Above 625 °C, bulk recrystallization led to Al diffusion through grain boundaries, disrupting the continuity of the oxide layer on the surface. These findings help further improve the existing alloy oxidation theory and develop potential surface modification methods on precious-metal-based alloys.

中文翻译：

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Al2Au 合金随温度变化的选择性氧化行为：定制 Au 增强氧化层的见解

选择性氧化是增强合金上保护性氧化层的常见策略。本工作在一系列温度下在Al ₂ Au 上获得了氧化膜，并对其结构、化学状态和耐腐蚀性进行了研究。氧化行为被证实与温度相关，表现出两种不同类型的氧化膜。在低于临界温度T _s (700 < T _s < 800 °C) 时发生均匀氧化，形成超薄氧化层 (<10 nm)，且金溶质原子增强了耐腐蚀性。在高于T _{s 的}温度下发生相分离氧化，导致由 Al ₂ O ₃和 AlAu相组成的更厚的氧化物影响区域 (250–300 nm) 。高于 625 °C，体相再结晶导致 Al 通过晶界扩散，破坏表面氧化层的连续性。这些发现有助于进一步完善现有的合金氧化理论，并开发贵金属基合金潜在的表面改性方法。