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

该奖项支持基础研究，为理解相变、塑性及其相互作用提供知识。该奖项下的研究将集中在硅和锗的相变和塑性方面。预测这些材料的变形响应对半导体工程具有重要意义。这项研究将导致一个多方面的计算工具，定量预测这些材料的性质。利用该计算工具进行计算机模拟，从原子到宏观层面揭示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，包括钢的热处理、形状记忆合金的行为和超硬陶瓷的合成。根据该奖项开发的软件将在该团队的网页和高性能计算集群上与研究界共享。研究小组还将参加新生荣誉计划，该计划将本科生与爱荷华州立大学的研究活动联系起来。将开设两门新的研究生课程，分别是相变和塑性，以及原子连续体建模。这项研究还将通过爱荷华州立大学工程学院的妇女与工程科学项目促进代表性不足群体的积极参与。本研究的目的是通过连接反应性并发原子连续体方法和连续相场方法建立预测多尺度建模框架。反应性并发原子连续体方法将基于原子场形式主义的有限元实现。同时相变和位错介导的塑性是化学键断裂和重整的结果，晶体结构和滑移的变化将模拟微米尺寸的硅和锗畴。相场方法将基于一种新的大应变多相热力学势，并将使材料中耦合相变和塑性的大规模模拟成为可能。在宏观尺度上模拟硅和锗中多相的形成和位错微观结构的演变。研究小组将通过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，通过定制材料的微观结构和控制应用加载条件来寻找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.