Phase constituents in Ni–Al–Co–Ti quaternary alloys

The phase constituents in Ni–Al–Co–Ti quaternary alloys with compositions of Ni (18.2–90.8), Al (0–9.2), Co (16.6–83.1) and Ti (0–16.9)(wt.%) at 750 °C and 1100 °C have been investigated in the samples, which were prepared by mixing two base alloys (Ni-9.2 wt.%Al and Co-16.9 wt.%Ti). Experimental results showed that disordered fcc γ and L12 ordered γ′ phases with a fcc/L12 structure formed in the quaternary alloys heat treated in the temperature range of 750–1100 °C. A partial isothermal phase diagram was plotted. The γ/γ′ two-phase structure existed continuously from Ni–Al side (Ni-9.2 wt.%Al) to Co–Ti side (Co-16.9 wt.%Ti). The obtained results could play an important role in the design and development of new high-temperature materials with an fcc/L12 structure.