Abstract High-temperature compressive experiments of a Ni-based superalloy containing δ phase (Ni3Nb) are conducted. The dynamic dissolution behavior of δ phase in hot deformation process is quantitatively investigated. The dissolution mechanisms of δ phase are analyzed by Transmission Electron Microscopy (TEM) and first-principles calculations. Results reveal that the dissolution of δ phase is accelerated with increasing deformation temperature or deformation degree. But, the dissolution of δ phase becomes weaken as the strain rate is raised. The shear modulus (G) and bulk modulus (B) of δ phase decrease with increasing temperature or reducing pressure. The positive Cauchy pressure (C12–C44) and the larger ratio of B/G (greater than 1.75) reveal that δ phase is ductile at high temperatures or pressures. The intense interactions between dislocations and δ phase induce the stress concentration and the rapid diffusion of Nb atoms, which accelerate the precipitation/dissolution of δ phase. A phenomenological model is established for depicting the dissolution behavior of δ phase in hot deformation process. The measured results are identical with the forecasted ones, which demonstrates the established model is feasible to accurately depict the dynamic dissolution behaviors of δ phase in hot deformation process.

中文翻译：

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时效镍基高温合金热变形过程中δ相的溶解机理和动力学

摘要 对一种含δ相(Ni3Nb)的Ni基高温合金进行了高温压缩实验。定量研究了热变形过程中δ相的动态溶解行为。通过透射电子显微镜 (TEM) 和第一性原理计算分析了 δ 相的溶解机制。结果表明，随着变形温度或变形程度的增加，δ相的溶解加快。但是，随着应变速率的提高，δ相的溶解变弱。δ相的剪切模量（G）和体积模量（B）随着温度升高或压力降低而降低。正柯西压力 (C12-C44) 和较大的 B/G 比值（大于 1.75）表明 δ 相在高温或高压下具有延展性。位错与δ相之间的强烈相互作用引起应力集中和Nb原子的快速扩散，从而加速δ相的析出/溶解。建立了描述热变形过程中δ相溶解行为的现象学模型。实测结果与预测结果一致，表明所建立的模型能够准确描述热变形过程中δ相的动态溶解行为。