The stacking-fault energy of short-range ordered γ-phase Ni-26.21Cr-2.02Mo-1.98W-4.19at%Re and Ni-26.07Cr-2.03Mo-1.98W-4.04at%Ru model alloys was studied. Using transmission electron microscope weak-beam observations and computer-simulated images of dissociation widths, the stacking-fault energy was determined as a function of temperature. The values for both alloys were close, being 31mJ/m2 for the Re-containing alloy and 28mJ/m2 for the Ru-containing alloy. In both cases, the dissociation widths remained almost constant up to 350C, while a slight decrease was observed at higher temperatures. The deformation micromechanisms and the constancy of the stacking-fault energy up to 750C were analysed in connection with short-range order. The deformation at low temperatures was characterised by dislocation pile-ups. The calculations revealed a strong effect upon the leading dislocation of the pile-up, whose dissociation distance could be reduced by 50% at most.

Stacking Fault Energy in Short-Range Ordered γ-Phases of Ni-Based Superalloys. F.Pettinari, J.Douin, G.Saada, P.Caron, A.Coujou, N.Clément: Materials Science and Engineering A, 2002, 325[1-2], 511–9