|About this Abstract
||2022 TMS Annual Meeting & Exhibition
||Grain Boundaries and Interfaces: Metastability, Disorder, and Non-Equilibrium Behavior
||Irrationalities and Non-unique Lattice Correspondences across Interfaces in Shape Memory Alloys
||Ahmedsameerkhan Mohammed, Sidharth Ravi, Wael Abuzaid, Hiroshi Akamine, Minoru Nishida, Huseyin Sehitoglu
|On-Site Speaker (Planned)
Shape Memory Alloys (SMAs) are phase-transforming materials capable of sustaining large reversible strains. Their reversibility depends on the motion of the transformation front and internal Twin Boundaries (TBs) in the transformed phase. We propose a thorough clarification of irrational internal TBs in 4 SMA alloys, revealing the partitioning of twinning shear on the irrational plane into shear on rational terraces and a non-trivial coherence strain on terraces. This coherence strain is relieved by an array of interface dislocations where the spacing between them can evolve with glide. The transformation front separates phases related by a lattice correspondence. TEM and EBSD observations in the new SMA, FeMnNiAl, independently observed the Nishiyama-Wasserman, Kurdjumov-Sachs and Pitsch correspondences revealing its non-unique nature. We explain all observations based on Habit-Plane-Variant (HPV) predictions from energy-minimization theory, noting that distinct correspondences can be obtained depending on internal structure of the transformed phase, whether twinned or faulted.
||Phase Transformations, Modeling and Simulation, Computational Materials Science & Engineering