A new paradigm for heat treatment of alloys

•The sign of the ordering energy in alloys varies with the temperature.•Each temperature of heating leads to formation of its characteristic microstructure.•Quenching of alloys is a totally unnecessary and useless operation.

The article considers the consequences in the field of heat treatment of alloys that could follow the introduction of the concept of phase transition ordering-phase separation into common use. By example of the Fe50Cr50 alloy, industrial carbon tool steel and Ni88Al12 alloy, it is shown that this transition occurs at a temperature, which is definite for each system, that the change of the sign of the chemical interaction between component atoms reverses the direction of diffusion fluxes in alloys, which affects changes in the type of microstructures. The discovery of this phase transition dramatically changes our understanding of the solid solution, changes the ideology of alloy heat treatment. It inevitably leads to the conclusion about the necessity of carrying out structural studies with the help of TEM in order to adjust the phase diagrams of the systems where this phase transition has been discovered. Conclusions have been made that quenching of alloys from the so-called region of the solid solution, which is usually performed before tempering (aging) is a completely unnecessary and useless operation, that the final structure of the alloy is formed during tempering (aging) no matter what the structure was before this heat treatment.