On the basis of microstructural observations of ½[110]-type jogged-screw dislocations, it had previously been proposed that the creep deformation mechanism in equiaxed γ-phase Ti–48Al alloys was controlled by the climb of the jogs on the dislocations. This was confirmed by the predictions of a creep model that was based upon the observations. Nevertheless, some of the assumptions of the model were not entirely supported by experiment or theory. The aim here was to check and confirm the parameters and dependences which were assumed by the model. The original solution was also reformulated so as to take account of the finite height of the moving jog, and the sub-structural model parameters were investigated in the light of this reformulation. The stress dependences of the dislocation density, jog spacing and jog height were evaluated by means of simulations, analytical modeling and experimental observations. The incorporation of all of these parameters and dependences into the reformulated model led to excellent predictions of creep rates and stress exponents.

Evaluation of the Jogged-Screw Model of Creep in Equiaxed γ-TiAl - Identification of the Key Sub-Structural Parameters. S.Karthikeyan, G.B.Viswanathan, M.J.Mills: Acta Materialia, 2004, 52[9], 2577-89