Effects of ternary elements on phase transformation and microstructure of NiAl/Ni3Al two-phase alloys

The microstructural evolution of the β-NiAl/γ′-Ni3Al two-phase was investigated in (Ni66Al34)100−χXχ (X=Ti, Si, Nb; χ=0-4 at.%) alloys. Three different microstructures, such as lamellar, mesh and Widmanstätten, were obtained with the phase transformation procedure which depends on the As (austenite start) temperatures and on the ternary elements. In the case of As>250 °C, lamellar microstructure was formed by the phase transformation, β′-martensite→Ni5Al3→β+γ′, in all the alloys. In the case of 20 °C