Phase transition “ordering–phase separation” in the Ni–12 at.% Al alloy

The microstructure of the Ni–12 at.% Al alloy heat treated at various temperatures has been studied. With transmission electron microscopy the clusters enriched with aluminum atoms were discovered in the microstructure after quenching from 1300 °C as a result of the tendency toward phase separation. Heat treatment at lower temperatures (700–1000 °C) results in precipitation of the Ni3Al chemical compound particles in the alloy. It is concluded that at the temperature somewhat above 1200 °C the phase transition “ordering–phase separation” takes place in the alloy causing the above changes in the microstructure.

► The phase separation microstructure is formed in the Ni–12 at.% Al alloy at 1300 °C. ► The ordering microstructure (Ni3Al particles) is formed in Ni-base solution at 1200 °C and below. ► The phase transition “ordering–phase separation” takes place at the temperature somewhat above 1200 °C.