ABSTRACT
This chapter presents the most important tool for the study of alloys: the phase diagram. Phase diagrams are maps, in the temperature-composition space, of the alloy constitution under conditions of thermodynamic equilibrium. The term constitution includes the phases and the composition of phases present in the system. With the aid of the phase diagram and for each alloy composition it is possible: to determine the fraction of phases and the composition of phases as a function of temperature; and to predict the changes in the alloy constitution for any change in temperature. It is also possible to determine parameters, which are useful for the processing of the alloy, such as liquidus, solidus and solvus temperatures, solidification ranges, eutectic, peritectic and eutectoid temperatures and invariant reactions, temperatures for the dissolution or precipitation of phases and intermetallic compounds, solubility limits and more.
