The dislocation-network theory of Harper-Dorn creep was reformulated by using a new equation for the kinetics of growth of individual dislocation links in the network. The new equation had no effect upon the previously derived scaled differential equation which predicted the distribution of link lengths. However, the new theory predicted slightly different behaviors for the kinetics of static recovery and led to a new equation for the strain rate; which was expressed in terms of parameters that could be evaluated independently. This equation was valid, not only for steady-state Harper-Dorn creep, but also for primary creep; provided that the instantaneous value of the dislocation density was known. Upon using data on the variation of dislocation density with time, calculated values of the creep rates for Al deformed in the Harper-Dorn regime, agreed with experimentally measured values; to within a factor of 2. Creep curves for Al were calculated with the same degree of accuracy, and these calculations involved no adjustable parameters. Steady-state creep rates for many materials, which presumably deformed in the Harper-Dorn creep regime, were compared with the strain-rate predictions of the new equation. The calculated values agreed with experimentally measured data to within a factor of about 150. This compared well with the performance of other proposed equations.

Predictive Capabilities of the Dislocation-Network Theory of Harper–Dorn Creep. M.A.Przystupa, A.J.Ardell: Metallurgical and Materials Transactions A, 2002, 33[2], 231-9