High-temperature creep in a coarse-grained oxide-dispersion strengthened Ni3Al alloy

An oxide-dispersion strengthened (ODS) Ni3Al(B)-alloy containing 5 at.% chromium, produced by powder metallurgy, was zone-annealed to produce a coarse-grained microstructure. The creep properties were then investigated between 1000 and 1200°C at creep rates from 10−7 to 10−3 s−1 and the resulting experimental data were compared with several models of creep deformation. As expected, the Rösler and Arzt model for the detachment of single dislocations from the dispersoids did not satisfactorily explain the measured data. The model of Göhring and Arzt, which considers superdislocations, as present in ordered Ni3Al, provided a much better correlation. The measured creep strengths were approximately five to ten times higher than those of fine-grained ODS-Ni3Al; however, they were about 1000 times lower than those of commercial Ni-based alloys such as MA 6000. Suggestions for further development and experiments are made.