Phase Equilibria\rFundamentals of Materials Science

Abstract

The appearance of a system can be homogeneous or heterogeneous. Even in equilibrium situations, involving that no further (net) changes in the system occur and are possible, provided the boundary conditions remain constant, heterogeneity can prevail: for example, in an Al–Si alloy at room temperature (and at 1 atm pressure), in equilibrium an Al-rich part of the system (f.c.c. crystals with very little Si dissolved) and a Si-rich part of the system (crystals of diamond-type structure with very little Al dissolved) can be distinguished. These, generally dispersed, parts of the system, which are in equilibrium with each other, will be called phases. Obviously there is a great scientific, fundamental interest and, even greater, practical/technological interest, to know and understand these “heterogeneous, phase equilibria”.