A modified dislocation mechanism for strengthening in Ni3Al alloys was suggested that accounts for temperature and strain rate effects. By this mechanism, thermal strengthening arose from an equilibrium density of small pinning points whose positions change rapidly with time due to thermal activation. These pinning points exert a uniform drag force on the glide of screw dislocations. An analytical expression for the yield strength was derived based upon the entropy created by these segments and the energy needed for cross slip from octahedral to cube planes. The analytical model was then compared to the observation of temperature-path history independence (i.e., thermal reversibility) in both single and polycrystalline Ni3Al. Such behavior was indicative of a deformation process which was largely governed by local dislocation segment mobility and not by the development of a deformation substructure. Temperature-path history independence, in addition to strain rate independence, was an inherent characteristic of the analytical derivation and, as such, appears to provide an intuitive description of the phenomenological processes which occur during initial plastic deformation of Ni3Al.

An Analytical Description for the Deformation Response of Ni3Al Alloys in the Anomalous Regime. Webb, G., de Bussac, A., Antolovich, S.D.: Metallurgical Transactions A, 1993, 24[2], 397-401