Understanding and Characterization of the Dynamic Deformation Behavior of Multiphase Metallic Microstructures using Virtual Diffraction*

Multiphase metallic materials of immiscible FCC-BCC systems synthesized using advanced manufacturing techniques allow for creating complex microstructures that can render a distribution of interfaces and metastable phases. The response of metastable phases under strain is likely an interplay between the deformation behavior through nucleation and evolution of dislocations/twins, and phase transformation. Understanding the governing factors of plasticity mechanisms and stability of non-equilibrium phases is essential to unravel the complexity of the deformation response. Recent efforts to investigate these behaviors have employed in-situ x-ray diffraction (XRD), where the microstructure can be analyzed through peak split, shift, and broadening, as well as new peak formation. However, the understanding of the role of interfaces and metastability of phases on the deformation mechanisms is still unclear. This study uses molecular dynamics to understand the mechanisms of plastic deformation in multiphase Cu-Fe and Cu-Mo microstructures with Cu clusters in a BCC matrix of Fe or Mo, and Fe or Mo clusters in an FCC matrix of Cu at high strain rates or shock loading conditions. In addition, virtual XRD is carried out to correlate the density of defects or fraction of phases to the changes of diffraction patterns. This talk will present our approach to fingerprint the contributions of various deformation modes, including twinning, dislocations, and phase transformations to the diffraction patterns.