Formation of diffusion micro-pairs in the Ni68Mo20Al12 alloy

Abstract

• The sign of the nteratomic interaction in a binary alloy changes with temperature. • Chemical bonds (ionic and covalent) exist in both solid and liquid states of an alloy. • New phases in ternary alloys form inside of diffusion micro-pairs formed in liquid. The article presents the results of an electron microscopic study of the Ni 68 Mo 20 A l 12 alloy. The results got serve as the basis for the conclusion that the chemical bonds between atoms in ternary alloys are carried out according to the principle of pair interaction. These data show that the separation of the studied ternary alloy into diffusion micro-pairs occurs already in the liquid state. When the temperature of the alloy drops to 1200 °C in the Mo/A l diffusion pair, the “ordering-phase separation” transition occurs, and Mo atoms and A l atoms take part in the formation of diffusion pairs with nickel. The article concluded that the starting point for the formation of the microstructure of alloys is the liquid state in which any alloy is in the process of its smelting. It is noted that high-entropy alloys, in which such diffusion micro-pairs cannot be formed due to hindered diffusion of atoms, are unlikely to have prospects for their use in industry.