Characterizing persistent slip bands in Al-Li alloys using DFXM

One of the hallmarks of fatigue is slip irreversibilities that culminate in unique defect arrangements during cyclic loading. Persistent slip bands (PSBs) are one such structure, although imaging of these defects has conventionally been performed on single crystals through transmission electron microscopy. In this proposed experiment, we will use a combination of 3DXRD (HEDM) and DFXM to characterize the mosaicity and elastic strain state of a fatigued specimen, in order to identify the 3D structure and micromechanical fields around a PSB which will help elucidate the drivers for fatigue failure. Prior work, by the PIs performed a similar experiment on a Ni-based superalloy, requiring an extraction of the grains of interest. Through lessons learned, we will fabricate an Al-Li specimen with tailored grain structure, specimen dimensions, and prior cyclic deformation to focus on the characterization of the PSB.