Pairwise interatomic interaction in alloys

The concepts of the physics of metallic alloys regarding the driving forces of diffusion phase transformations, the nature of solid solutions, the chemical interatomic interaction energy, the principles of plotting phase diagrams, and the principles of heat treatment of alloys are critically reviewed. The ordering–separation phase transition, which is caused by the recently detected property of alloys to change the sign of chemical interatomic interaction when temperature changes, is shown to change these concepts radically. The experimental data that fully support the ideas advanced in this review are presented (comprehensive experimental data for Ni–Cr and $\rm Co_3V$ alloys are presented). The problem of the diffusion processes in multicomponent alloys is considered in detail. They are shown to occur according to the model of pairwise chemical interatomic interaction. The formation of diffusion couples in a multicomponent alloy begins in its liquid state. When temperature decreases, this process occurs in each diffusion couple similarly to the phase formation in the corresponding binary alloys.