Structural-thermodynamic method of phase analysis of multicomponent alloys based on the example of the Ni50Со25Мо25 alloy

• A structural-thermodynamic method of multicomponent alloys phase analysis is proposed.
• In the Ni50Со25Мо25 alloy, crystalline Mo particles precipitate in liquid solution.
• In the liquidus–solidus range, the Со3Мо chemical compound precipitates.
• Below 1200 °C, the Ni2Mo chemical compound precipitates in the alloy.
• Clusters of cobalt atoms are formed in the alloy at all temperatures above 600 °C.

A structural-thermodynamic method of phase analysis of multicomponent alloys is proposed. The method is based on the use of the model of pairwise interaction and experimental determination of the sign of pairwise chemical interaction and includes an electron microscopic study of microstructures above and below the temperature of phase transition ordering-phase separation for each of the diffusion couples. The method is demonstrated on the example of the Ni50Со25Мо25 alloy. It is shown what precipitates are formed in the investigated alloy over the whole temperature range of heat treatment including the liquid state. We can conclude that structural data obtained in other works, for alloys, to some extent similar in composition to the alloy studied, are far from the results obtained in the present paper.