This CAREER award supports an integrated research and educational project to develop new computational approaches to study the defect-solute interactions and their effects on mechanical properties of advanced transition metal alloys by bridging the gaps between electronic, atomistic and mesoscale levels. Interactions between solute atoms and crystalline defects (dislocations, twin/grain boundaries, etc.) play essential roles in determining the mechanical and physical properties of many advanced alloys. Recently, our group discovered a series of strong correlations between defect energetics and local electronic structures in several types of advanced transition metal alloys. These new findings provide the means to predict the complex defect-solute interactions accurately by understanding the chemical bonding mechanisms at the electronic level. Based on this new discovery, the proposed research will (i) identify generalized and quantitative correlations between local electronic/atomistic structures and defect-solute interactions for multiple types of defects and solutes based on chemical bonding models, first-principles calculations and machine learning methods, (ii) apply the above correlations to construct mesoscale simulation methods and phenomenological models to predict the solute/impurities effects on defect stability and mobility, and (iii) employ the above methods and models to evaluate the mechanical behavior, such as solid-solution hardening/softening, twinability, and grain boundary embrittlement.
Qi’s group is involved in the PRedictive Integrated Structural Materials Science Center (PRISMS), a DOE-BES funded research center dedicated to integrated computational and experimental studies of structural alloys located at University of Michigan. One major task of our group is to apply atomistic simulations to understand the interactions between dislocations and grain boundaries (GBs) in Mg and Mg alloys. We are developing an efficient genetic algorithm for predicting the minimum energy structures of GBs by considering both macroscopic and microscopic degrees of freedom for pure metals and alloys. Based on these GB structures, atomistic simulations are performed to investigate the alloying effects on GB-dislocation interactions and the corresponding mechanical behavior variations (Hall-Petch Relation, etc.).
