Interactions of Multiple Phase Transformations and Dislocations: Modeling and Simulation from Atomistic to Microscale

该奖项支持基础研究，以提供了解相变、可塑性及其相互作用的知识。该奖项下的研究将集中在硅和锗的相变和可塑性。预测这些材料的变形响应对半导体工程具有重要意义。这项研究将带来一种多方面的计算工具，用于定量预测这些材料的性能。由该计算工具实现的计算机模拟将揭示从原子到宏观水平相变与塑性相互作用的主要机制。作为扩展，该计算工具还可以应用于其他材料工艺和技术，包括钢的热机械处理、形状记忆合金的行为以及超硬陶瓷的合成。根据该奖项开发的软件将在团队的网页和高性能计算集群上与研究社区共享。研究团队还将参与新生荣誉计划，该计划将本科生与爱荷华州立大学的研究活动联系起来。将开发两门新的研究生课程，内容涉及相变和塑性，以及原子-连续介质建模。这项研究还将通过爱荷华州立大学工程学院的妇女和工程科学方案，促进代表性不足群体的积极参与。本研究的目的是通过将反应性并发原子-连续体法和连续相场法相结合，建立一个预测性的多尺度建模框架。反应式并行原子-连续体方法将基于原子场形式的有限元实现。同时的相变和位错介导的塑性由于化学键的断裂和重整，晶体结构的变化和滑移将被模拟为微米级的硅和锗的磁畴。相场方法将基于一种新的大应变多相热力学势能，并将能够大规模模拟材料中的耦合相变和塑性。将在宏观尺度上模拟硅和锗中多相的形成和位错微结构的演化。研究小组将通过完全原子模拟和实验测量来验证多尺度计算工具的预测能力。最后，该团队将应用多尺度模拟工具，通过调整材料的微观结构和控制加载条件，找到促进或抑制位错活动和相变的方法。

This award supports fundamental research to provide knowledge toward understanding phase transformations, plasticity, and their interactions. The research under this award will focus on phase transformation and plasticity in silicon and germanium. Predicting the deformation response in these materials is important for semiconductor engineering. This research will lead to a multifaceted computational tool for quantitative predictions of properties of these materials. The computer simulations enabled by the computational tool would reveal the main mechanisms during the interaction between phase transformation and plasticity from the atomic to the macroscopic level. As an extension, the computational tool can also find applications to other material processes and technologies, including the thermomechanical treatment of steel, the behavior of shape memory alloys, and the synthesis of superhard ceramics. The software developed under this award will be shared with the research community on the team's webpages and high performance computing clusters. The research team will also participate the Freshman Honor Program that connects undergraduates with research activities at Iowa State University. Two new graduate courses on phase transformations and plasticity, and atomistic-continuum modeling will be developed. This research will also promote active participation from under-represented groups through the Program for Women and Science in Engineering in the College of Engineering at Iowa State University. The objective of this research is to establish a predictive multiscale modeling framework by linking a reactive concurrent atomistic-continuum method and a continuum phase field approach. The reactive concurrent atomistic-continuum method will be based on a finite element implementation of an atomistic field formalism. Simultaneous phase transformations and dislocation-mediated plasticity as a consequence of chemical bond breaking and reforming, changes of the crystal structures and slip will be simulated for micron-sized domains of silicon and germanium. The phase field approach will be based on a new multiphase thermodynamic potential for large strains and will enable large-scale simulations of coupled phase transformation and plasticity in materials. Formations of multiple phases and evolutions of dislocation microstructures in silicon and germanium will be simulated at the macroscale. The research team will validate the predictive capability of the multiscale computational tool through fully atomistic simulations and also experimental measurements. Lastly, the team will apply the multiscale simulation tools to find methods for promoting or suppressing dislocation activities and phase transformations through tailoring the microstructures of materials and controlling applied loading conditions.