The effect of heat treatments on the structure of a metal alloy is an important field in materials science and its compression is crucial to obtaining the desired characteristics with greater accuracy.
The binary or ternary state diagrams of an alloy are not sufficient to predict which phases will be obtained after the treatment cycle since they foresee the phases in equilibrium conditions as a result of long periods at certain temperatures. What happens in the practice of heat treatments is that at certain cooling rates different metastable structures are obtained which give the material the required characteristics.
The addition of a controlled atmosphere in the furnace chamber changes the chemical composition of the surface layer of the alloy, this process is defined as a thermochemical treatment.