Phase Heritage: Deciphering Evidence of Pre-Existing Phases via Inherited Crystallographic Orientations

Timms, Nicholas E ; Erickson, Timmons M ; Pearce, Mark A ; Cavosie, Aaron J ; Cayron, Cyril ; Reddy, Steven M ; Zanetti, Michael R

关键词: PHASE TRANSFORMATIONS;    CRYSTALLOGRAPHY;    CRYSTAL STRUCTURE;    ZIRCONIUM OXIDES;    COMPUTER PROGRAMS;   

RP-ID  :  JSC-E-DAA-TN60138

学科分类：空间科学

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

The concept of 'phase heritage' (e.g., Timms et al., 2017a) involves microstructural recognition of the former presence of a phase that has since transformed to another via evidence encoded in crystallographic orientations. Phase heritage relies on the phenomenon that newly grown (daughter) phases nucleate with particular crystallographic orientation relationships with the preceding (parent) phase. This phenomenon is common for displacive (i.e., shear or martensitic) transformations, well documented in the metals and ceramics literature, but is relatively uncommon in geosciences. This presentation outlines the concepts behind this approach, showcases results from software for automated analysis of EBSD data, and illustrates examples of polymorphic and dissociation phase transformations in the ZrSiO4-ZrO2-SiO2 system, which has particularly useful applications for 'extreme thermobarometry' in impact environments (Timms et al., 2017a).