|About this Abstract
||Materials Science & Technology 2019
||Phase Transformations in Ceramics: Science and Applications
||In Situ Investigation of Stress-Induced Martensitic Transformation in Granular Shape Memory Ceramics
||Hunter Rauch, Yan Chen, Ke An, Hang Yu
|On-Site Speaker (Planned)
Stress-induced martensitic transformation readily occurs in granular shape memory materials, when individual particles experience high stresses and transform from a high-symmetry austenite phase to a low-symmetry martensite phase. Compared to monolithic solids, however, the driving force is highly heterogeneous and the mechanical constraint for martensite nucleation is low. Using in situ neutron diffraction, here we study this phenomenon in granular shape memory ceramics consisting of single-crystal micro-particles of ZrO2-12at%CeO2 and ZrO2-15at%CeO2. By examining how the phase fraction, lattice strain, and integral peak broadness evolve during external loading, unloading, and subsequent heating, several peculiar features are discovered, such as continuous mode of transformation and strong correlation between the peak broadening and the transformed phase fraction. We discuss the mechanism for martensite nucleation and growth in granular packings and propose a model for stress-induced martensitic transformation in granular shape memory materials.
||Definite: At-meeting proceedings