The creep behavior of a directionally solidified multicomponent Ni3Al alloy was investigated at 923 to 1173K. The dislocation structure during secondary stage creep was examined by transmission electron microscopy. At lower temperatures from 923 to 1023K under a stress of 500MPa, there existed a number of dense three-dimensional dislocation networks in the Ni3Al creep specimen while, at a higher temperature of 1173K under a stress of 200MPa, the dislocation structure degenerated into regular two-dimensional dislocation networks. Climb of dislocations occurred in the overall test temperature range. The stress dependence and temperature dependence of the creep rates for the Ni3Al alloy were also determined. It was found that power law creep was obeyed with the stress exponent equal to 4.7 and the activation energy equal to 326.6kJ/mol. The climb of dislocations was suggested to be the rate controlling factor for the secondary stage creep rate.

Creep Behavior of a Directionally Solidified Ni3Al Alloy. Zhang, Y., Lin, D.: Materials Research Society Symposium – Proceedings, 1993, 288, 611-6