Thermodynamics of Phase Change

This chapter introduces classical thermodynamics of phase changes, which are referred to as phase transformations within the macroscopic science associated with energy change of matter during a process being influenced by temperature and pressure. In principle, thermodynamics describes the conservation of mass, conservation of energy, and the conversion of energy and defines the physical state of matter. Most phase changes henceforth are related to melting and solidification of metals and their alloys. Moreover, a phase change is also known as phase transition accompanied by energy transformation. Eventually, metallic substances can also be subjected to phase changes at temperatures and pressures. Commonly, a metal can undergo melting as a solid-to-liquid or solidification as a liquid-to-solid phase change carried out at atmospheric pressure. In practice, a thermodynamic system can be designed and analyzed to produce energy as in a power plant or to study the thermodynamic process related to phase change as in solidification of pure metals and their alloys. The goal in this chapter is to describe phase transformation (phase change) during solidification (freezing) using thermodynamic principles and formulations. This leads to the assessment of nucleation of particles and their atomic arrangement of atoms called lattice.