Think about how the different phase fields result from changes in energy with temperature. Sometimes a combination of liquid and solid will have a lower energy (shown by the black tie-line) than either liquid or solid alone. The brown lines in the energy diagram are the energy of the solid phase, the blue lines are the energy of the liquid phase. Take some time (more than just a few minutes-there's a lot to read and understand!!) to work through the illustrations below, figuring out what they mean. The lowest energy phase, or combination of phases, is the phase or phases that will be stable at a particular temperature and composition. Notice how the energy decreases toward the middle composition of solutions-this is a consequence of the entropy of mixing. The lower row of images shows the qualitative energy of the different phases plotted as a function of the composition of the phase. In the illustrations below, the upper row of images shows the phase diagram. We considered how the diagram reflects relative volumes and entropy.Ģ-component diagrams also reflect the energy states of the the phases, with the phases that are stable under any particular set of conditions being the phases with the lowest energy (where energy reflects the enthalpy and entropy of the phases as well as an entropy effect due to mixing of components within phases that have either liquid or solid solution. In our previous lesson, we considered briefly the relationship between Gibbs Free Energy and the lines and regions on 1-component phase diagrams. The relationship between energy of phases and phase diagrams for 2-component phase diagrams Manufacture of steel requires the formation of austenite and its recrystalliization at the eutectic into a mixture of ferrite and cementite. Phase diagram used to understand the manufacture of steel, a process begun over 3200 years ago. Mineralogy-More Phase Diagrams, Free Energy Diagrams, plus 3 and 4 Component Phase Diagrams

Feldspar ternary diagram