Determination of stacking fault energies of Ni-Cr-Ce alloys

The effect of Ce on the stacking-fault energy of Ni-Cr alloys is presently ascertained by the weak-beam method; TEM characterization results are compared with published data. A trend is noted which opposes the direction of the observed decrease in creep rate, indicating that diffusional flow is primarily affected by the Ce despite the very low Ce concentrations in question (119 at. ppm). The trend nevertheless fits the observed creep-activation energy increase. A similar effect is obtained with 225 at. ppm additions of Y to Ni-22Cr, where Y reduces Cr and Ni tracer diffusivities. 15 refs.