Understanding the kinetics of static recrystallization in Mg-Zn-Ca alloys using an integrated PRISMS simulation framework
University of Michigan（密歇根大学）
David Montiel, Philip Staublin, Supriyo Chakraborty, Tracy Berman, Chaitali Patil, Michael Pilipchuk, Veera Sundararaghavan, John Allison, Katsuyo Thornton
备注：
37 pages, 12 figures. Includes Supplementary Information section
Recrystallization is a phenomenon in which a plastically deformed polycrystalline microstructure with a high dislocation density transforms into another that has low dislocation density. This evolution is driven by the stored energy in dislocations, rather than grain growth driven by grain boundary energy alone. One difficulty in quantitative modeling of recrystallization is the uncertainty in material parameters, which can be addressed by integration of experimental data into simulations. In this work, we compare simulated static recrystallization dynamics of a Mg-3Zn-0.1Ca wt.% alloy to experiments involving thermomechanical processing followed by measurements of the recrystallization fraction over time. The simulations are performed by combining PRISMS software for crystal plasticity and phase-field models (PRISMS-Plasticity and PRISMS-PF, respectively) in an integrated computational materials engineering framework. At 20% strain and annealing at 350 °C, the model accurately describes recrystallization dynamics up to a mobility-dependent time scale factor. While the average grain boundary mobility and the fraction of plastic work converted into stored energy are not precisely known, by fitting simulations to experimental data, we show that the average grain boundary mobility can be determined if the fraction of plastic work converted to stored energy is known, or vice versa. For low annealing temperatures, we observe a discrepancy between the model and experiments in the late stages of recrystallization, where a slowdown in recrystallization kinetics occurs in the experiments. We discuss possible sources of this slowdown and propose additional physical mechanisms that need to be accounted for in the model to improve its predictions.
Effect of annealing on the corrosion-fatigue strength and hot salt corrosion resistance of fine-grained titanium near-α alloy Ti-5Al-2V obtained by Rotary Swaging
Atomic-Scale Insights into Solute Drag Effects on Grain Boundary Motion in Mg-Al and Mg-Ca Alloys
College of Materials Science and Engineering, State Key Laboratory of Cemented Carbide, Hunan University（湖南大学材料科学与工程学院）；McGill University（麦吉尔大学）；Institute of Solid State Physics, Chinese Academy of Sciences（中国科学院固体物理研究所）；School of Physics and Electronics, Hunan University（湖南大学物理与电子学院）；Hunan University（湖南大学）
Interstitial-mediated dislocation climb and the weakening of particle-reinforced alloys under irradiation
位错可以通过吸收（或发射）点缺陷（空位和自填隙原子（SIAs））爬出其滑移面。与保守的滑翔运动相反，爬升依赖于点缺陷的热扩散，因此在更长的时间尺度上运行，导致某些形式的蠕变。虽然平衡点缺陷浓度允许位错爬升以减轻非滑移应力，但点缺陷过饱和也会导致渗透力，即使在没有外部应力的情况下也会驱动位错运动。自填隙原子通常具有比空位高得多的形成能，因此它们对爬升的贡献通常被忽略。然而，在辐照条件下，这两种类型的缺陷以相等的数量非热地产生。在这封信中，我们使用简单的热力学参数来表明，在辐照材料中的贡献不可忽略，并且它们对位错引起的渗透力比空位引起的渗透力大许多个数量级。这就解释了为什么{ \it in situ}透射电子显微镜辐照观察到的棱柱形位错环更多的是间隙型而不是空位型。使用离散位错动力学模拟，我们调查的影响，位错障碍物的相互作用，并发现在许多数量级的脱钉时间减少。这对辐照下颗粒增强合金的强度具有重要影响。
