High-resolution transmission electron microscopy of precipitate plate growth by diffusional and displacive transformation mechanisms

High-resolution transmission electron microscopy (HRTEM) is used to investigate the atomic structure of precipitate plates formed by diffisional and displacive transformations in alloys. Comparison among several fcc → hcp diffusional transformations illustrates the capability of HRTEM for understanding the mechanisms of the compositional and structural components of the transformation at the atomic level. Similar analyses are performed for a fcc → bct displacive transformation, and the sensitivity of HRTEM to local changes in composition and strain are discussed.