High‐temperature treatment of γ‐Al₂O₃ can lead to a series of polymorphic transformations, including the formation of δ‐Al₂O₃ and θ‐Al₂O₃. Quantification of the microstructure in the range where δ‐ and θ‐Al₂O₃ are formed represents a formidable challenge, as both phases accommodate a high degree of structural disorder. In this work, we explore the use of an XRD recursive‐stacking formalism for the quantification of high‐temperature transition aluminas. We formulate the recursive‐stacking methodology for modelling of disorder in δ‐Al₂O₃ and twinning in θ‐Al₂O₃ and show that explicitly accounting for the disorder is necessary to reliably model the XRD patterns of high‐temperature transition alumina. We also use the recursive stacking approach to study phase transformation during high‐temperature (1050 °C) treatment. We show that the two different intergrowth modes of δ‐Al₂O₃ have different transformation characteristics and that a significant portion of δ‐Al₂O₃ is stabilized with θ‐Al₂O₃ even after prolonged high‐temperature exposures.

中文翻译：

---

高温转变Al2 O3的定量及其相变。

的γ-Al的高温处理₂ ö ₃可导致一系列多晶型转变，包括δ-Al系的形成₂ ö ₃和θ-Al系₂ ö ₃。在δ-和θ-Al系的范围中的微结构的定量₂ ö ₃形成表示一个严峻的挑战，因为两相适应高度的结构紊乱。在这项工作中，我们探索了使用XRD递归堆积形式来量化高温过渡氧化铝的方法。我们制定递归堆叠方法在疾病的造型δ-Al系₂ Ø ₃和结对的θ-Al系₂O ₃并表明显式地解释该紊乱对于可靠地模拟高温过渡氧化铝的XRD图案是必要的。我们还使用递归堆叠方法研究高温（1050°C）处理期间的相变。我们表明，δ-Al的两个不同的共生模式₂ ö ₃具有不同的转换特性和的δ-Al系一显著部₂ ö ₃稳定用θ-Al系₂ ö ₃即使经过长时间的高温暴露。