Deformation twinning is observed in numerous engineering, chemical, and geological materials. While B2 compounds are well known to be brittle, some rare-earth systems exhibit anomalous ductility. Order-disorder transformations and miscibility gaps, with their resulting microstructure, are ubiquitous in metals, e.g., rapid kinetics of gamma precipitates formation in Aluminum. The common connection: All these phenomena can be predicted quantitatively IF accurate defect energetics and potential energy surface (atomic scale) details are incorporate directly into defect-mediated (mesoscale scale) physics that control the behavior. To exemplify we show examples in magnetic-storage alloys, twinning in in fcc solid solutions, anomalous ductility in B2 compounds, and precipitate formation in solid solution aluminum alloys, including kinetics, using density-functional theory defect calculations and analytically derived multiscale models.
*Support from U.S. Department of Energy, Basic Energy Sciences (Materials Sci. and Eng., DEFG02-03ER460626) and through Ames Laboratory (DE-AC02-07CH11358), operated by Iowa State University, and by NSF (DMR-0705089).