A mechanism was proposed for the anelastic relaxation effect which had been observed at high temperatures. The known dependence of the magnitude of relaxation upon the crystal orientation strongly suggested that the effect was due to the stress-induced redistribution of point defects on the sub-lattice Ni-atom sites. Both the kinetic and thermodynamic aspects of the relaxation could be explained quantitatively in terms of the reorientation of antisite Al atoms. The properties of point defects which were relevant to the effect were calculated by using a thermodynamic model of Brag-Williams type and by means of atomistic computer simulation. The rate and magnitude of the relaxation which was observed was in reasonable agreement with theoretical values that were estimated from the results of these calculations.

On the Origin of the Anelastic Relaxation Effect in Ni3Al. Numakura, H., Kurita, N., Koiwa, M., Gadaud, P.: Philosophical Magazine A, 1999, 79[4], 943-53