Elevated temperature creep deformation in solid solution strengthened 〈0 0 1〉 NiAl–3.6Ti single crystals

The 1100–1500 K slow plastic strain rate compressive properties of 〈0 0 1〉 oriented NiAl–3.6Ti single crystals have been measured, and the results suggests that two deformation processes exist. While the intermediate temperature/faster strain rate mechanism is uncertain, plastic flow at elevated temperature/slower strain rates in NiAl–3.6Ti appears to be controlled by solute drag as described by the Cottrell–Jaswon solute drag model for gliding b=a0〈1 0 1〉 dislocations. While the calculated activation energy of deformation is much higher (∼480 kJ/mol) than the activation energy for diffusion (∼290 kJ/mol) used in the Cottrell–Jaswon creep model, a forced temperature-compensated power law fit using the activation energy for diffusion was able to adequately (>90%) predict the observed creep properties. Thus, we conclude that the rejection of a diffusion controlled mechanism cannot be simply based on a large numerical difference between the activation energies for deformation and diffusion.