Rapid solidification of Ni3Al produces a network of curved antiphase boundaries. Annealing, which allows a closer to equilibrium structure to develop, results in the antiphase boundaries aligned preferentially on {100} planes; thus indicating that the antiphase boundary energy was less on {100} planes than on other planes. This provides the first direct experimental evidence of an antiphase boundary energy anisotropy which forms the basis of the Kear-Wilsdorf cross slip model used to explain the increase in yield stress with an increase in temperature.Anisotropic Antiphase Boundaries in Rapidly Solidified Ni3Al. Horton, J.A., Liu, C.T.: Acta Metallurgica, 1985, 33[12], 2191-8