3D In-Situ Characterization of Individual Grains in CuAlNi Shape Memory Alloys during Cyclic Loading Using X-Ray Topotomography

Abstract The crystallographic theory of martensite (CTM) forms the foundation of our understanding of stress-induced reversible martensitic phase transformation cycling, relying on assumptions that exclude precipitates, grain boundaries, plasticity, and strained lattices. An ongoing challenge persists in adapting our understanding of CTM-based micromechanical theory (e.g., habit plane variant, or HPV, prediction and the origins of hysteresis and, subsequently, functional fatigue) to real, engineering-grade SMAs. Due to the complexity, elucidating the micromechanical phenomena requires novel high-resolution 3D in-situ characterization techniques.