Freezing diagrams: Part I. Development and Implications for glass formability

Prediction of equilibrium and metastable phase formation for a particular system, after cooling from the liquid state, is possible by the development of afreezing diagram. the freezing diagram is constructed by consideration of kinetic as well as thermodynamic factors. The kinetic factors divide the diagram into three zones. These are: (1) where long-range diffusion can occur; (2) where short-range diffusion only is possible; and (3) where no significant diffusion is possible in the liquid ahead of the solid-liquid interface. The solid-liquid interface temperature,T ₁ , determines which diffusion process occurs.T ₁ is the vertical axis of the diagram plotted against composition. the microstructure that results is predicted by the thermodynamic possibilities in each kinetic zone. In the first zone, the equilibrium phase diagram is applicable. The second zone only allows massive transformations to single-phase structures, and their limits are defined byT _o lines. The third zone is below the glass transition temperature, and any liquid retained to this zone is quenched-in and becomes a glass. The development, significance, and limitations of the freezing diagram are discussed.