Ni3Al precipitation behavior in the two-phase (NiAl+Ni3Al) alloy

The toughness of brittle intermetallics has been improved by controlling the morphologies of the Ni3Al through the solution and aging treatment in (NiAl+Ni3Al) two-phase alloy. In this study, changes in the Ni3Al morphologies were attempted through variation of the heat treatment conditions. The microstructure was examined using optical and scanning electron microscopy and the phase was characterized by X-ray diffraction analysis. Our results indicated that the precipitation of the homogeneous and randomly-oriented Ni3Al during the final aging treatment could be made possible by performing an isothermal transformation of NiAl- (B2) to Ni5Al3 single phase prior to the final aging treatment in Ni-34at.%Al alloy.