ABSTRACT In this work, we combine a generic alloy-by-design model with a novel concept, the nucleation barrier for the formation of Laves phase to fill the creep cavities, in order to develop multi-component creep resistant steels with kinetically tuned self-healing behaviour. In the model the high-temperature long-term strength is estimated by integrating precipitation strengthening due to M23C6 carbides and solid solution strengthening, while the optimized compositional solutions are determined by employing the coupled thermodynamic and kinetic principles. W-containing Laves phase herein is selected as the self-healing agent to autonomously fill the grain boundary cavities, so as to prolong the creep lifetime. To achieve the effective healing reaction, the nucleation time for Laves precipitates are expected to coincide simultaneously with which creep cavities start to form or reach a healable size. Using experimental data from literature, an empirical relationship to estimate the incubation time for Laves phase formation has been constructed, from which the thermodynamic driving force for onset of precipitation as a function of temperature and intended precipitate nucleation time was derived. Three sample alloys have been selected among the desirable solutions, which are predicted to have the same strength but widely different Laves phase nucleation times. The calculations are also performed for different use temperatures to explore the compatibility between high temperature strength and timely cavity filling behaviour. In its current form the model is not expected to yield the truly optimal composition but to demonstrate how the kinetics of the healing reaction can affect the predicted optimal alloy compositions.

中文翻译：

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计算设计含 W 自愈铁素体抗蠕变钢的第一步

摘要在这项工作中，我们将通用合金设计模型与新概念（形成 Laves 相的形核势垒以填充蠕变腔）相结合，以开发具有动力学调谐自润滑的多组分抗蠕变钢。愈合行为。在该模型中，高温长期强度是通过整合 M23C6 碳化物的沉淀强化和固溶强化来估算的，而优化的成分解决方案是通过采用热力学和动力学耦合原理来确定的。本文选用含钨 Laves 相作为自愈剂，自主填充晶界空腔，延长蠕变寿命。为了达到有效的愈合反应，Laves 析出物的成核时间预计与蠕变腔开始形成或达到可愈合尺寸同时发生。使用文献中的实验数据，已经构建了估计 Laves 相形成的孵化时间的经验关系，从中推导出作为温度和预期沉淀成核时间函数的沉淀开始的热力学驱动力。在理想的解决方案中选择了三种样品合金，预计它们具有相同的强度，但 Laves 相成核时间却大不相同。还针对不同的使用温度进行了计算，以探索高温强度和及时的空腔填充行为之间的兼容性。