Alloying and the micromechanics of Co–Al–W–X quaternary alloys

The lattice misfit and diffraction elastic constants in hot rolled polycrystalline Co–7Al–5W–2Ta and Co–6Al–6W–2Ti (at.%) are measured using neutron and synchrotron X-ray diffraction. The misfit in the two alloys was found to be +0.67 and +0.59%, using neutron diffraction at HRPD. The misfit was found to increase with temperature, as in Ni superalloys. This implies that the amount of coherency strengthening increases with temperature. The diffraction elastic constants measured show that the γ′ phase is less stiff than the γ matrix in all orientations, which means that load shedding will occur to the γ phase.