A1-L12 structures in the Al-Co-Ni-Ti quaternary phase system

Abstract

The phase constituents of alloys from the (Ni,Co)85(Al,Ti) 15 plane of the Ni-Co-Al-Ti quaternary system were investigated following prolonged exposure at 750°C. Microstructural investigations confirmed the existence of a continuous A1-L12 two-phase region in the Ni-Co-Al-Ti quaternary system between Ni-Ni3Alif and Co-Co 3Ti. The lattice misfits of alloys from this quaternary system were determined using neutron diffraction. With increasing contents of Ti the positive lattice misfit increases up to +0.79% in the Ti-containing alloys, which leads to an increasing tetragonal distortion of the γ matrix phase due to the increasing coherency stresses. © (2011) Trans Tech Publications Switzerland.