Abstract
Phase equilibrium in a two-phase stressed coherent solid is analyzed using the thermodynamic equilibrium conditions directly. Subject to the constraints of constant temperature and external pressure, a bulk alloy composition is chosen and the corresponding volume fractions and phase compositions that satisfy the equilibrium conditions are obtained. A number of equilibrium states (combinations of volume fractions and phase composition) may exist that yield energy minima for a given temperature, pressure, and composition. These multiple metastable states may lead to a nonuniqueness in the observed physical state of the system. Discontinuous jumps in precipitate volume fraction between 0 and 1 as well as jumps within the range 0 to 1 are possible with a smooth variation in alloy composition. These results are a consequence of the elastic energy, and thus the system energy, being a function of the volume fraction when two phases coexist as coherent solids. The concept of a phase stability diagram is introduced for displaying and analyzing the equilibirum conditions in coherent solids. The influence of elastic homogeneity and the form of the free energy curves as a function of composition in the absence of stress are examined.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1213-1228 |
| Number of pages | 16 |
| Journal | Metallurgical transactions. A, Physical metallurgy and materials science |
| Volume | 18 A |
| Issue number | 7 |
| DOIs | |
| State | Published - Jan 1 1987 |
ASJC Scopus subject areas
- Engineering(all)