Correlating deformation mechanisms with X-ray diffraction phenomena in nanocrystalline metals using atomistic simulations

Abstract

Virtual X-ray diffraction (XRD) and atomistic simulations are used to probe the relationship between XRD phenomena and the strain accommodation methods associated with deformation. Twinned and untwinned nanocrystalline (NC) samples loaded in tension reveal distinct XRD responses. In initially untwinned samples, peak splitting occurs precisely as dislocation mediated deformation mechanisms initiate at approximately 2.9% strain. However, initially pre-twinned samples reveal less dislocation mediated deformation and no observable XRD peak splitting. XRD responses from control sets of ideal defect structures representing bulk and unloaded NC samples are analyzed. This study shows that the peak splitting during deformation of the initially untwinned NC sample can be traced to both the high density of planar defects and the complex internal strain state present under external load.