MSE Colloquium: Ashley Bucsek, Investigation of Deformation Processes in Shape Memory Alloys Using 3D X-Ray Diffraction and X-Ray Microscopy
In the case of shape memory alloys (SMAs), fundamental micromechanical theory has been an active area of research for more than 70 years. However, experiments to validate these theories on the microstructural scale are relatively new, challenging, and often limited to two-dimensional surface measurements. As a result, there persists a general lack of understanding regarding the relationships that link microstructure evolution to macroscopic behavior. To address this open area, we utilize cutting-edge in situ synchrotron X-ray techniques such as near-field and far-field 3D X-Ray Diffraction (3DXRD) and Dark-Field X-Ray Microscopy (DFXM). Using these techniques, I present results from three particular experiments on NiTi SMAs: (1) The micromechanics behind localized deformation bands in martensite reorientation are reported using 3DXRD, revealing a geometric softening effect across the band interfaces; (2) A forward model algorithmic approach to indexing martensite in two-phase 3DXRD data is presented and used to illustrate the shortcomings of the maximum work criterion; (3) The topology, misorientation, and elastic strains inside an austenite single crystal during thermally-induced transformation are shown using DFXM with a spatial resolution of 100 nm.
Ashley Bucsek is an NSF Graduate Research Fellow and Mechanical Engineering Ph.D. candidate at Colorado School of Mines. She studies relationships between microstructure evolution and macroscopic twinning and phase transformation behaviors in alloys. Current research thrusts include micromechanical theory and in situ, multiscale characterization of ferroic and multiferroic materials. She has developed modern synchrotron diffraction techniques for studying these complex material systems at the Advanced Photon Source, Cornell High Energy Synchrotron Diffraction Source, Advanced Light Source, and European Synchrotron Radiation Facility. Most recently, Ashley spent the end of 2017 working as a visiting scientist on beamline ID06 at the European Synchrotron Radiation Facility as an NSF-GROW recipient. Here, she conducted the first-ever Dark-Field X-Ray Microscopy experiments on shape memory alloys. She is the Student Board Member on the Board of ASM’s International Organization on Shape Memory and Superelastic Technologies.