Crystallography and Energetics of Second Phases and Interfaces

Morphology and crystallography of second phases, such as precipitates, martensites, inclusions, etc., embedded in a parent phase are discussed. The contribution of elastic strain energy is considered to find the most favorable shape of a second phase for given eigenstrains and elastic constants. Analyses based on the idea of invariant plane and invariant line deformations are conducted to discuss crystallography and energetics of second phases. Simple criteria are proposed to explain orientation relationship between the second phase and the parent phase as well as epitaxial relationship for substrate/thin film systems. Two types of stress effects are discussed; one on the morphology of the second phase and the other on variant selection.