INTERPRETATION OF STEADY-STATE CREEP RATE IN MECHANICALLY ALLOYED AL-C-O ALLOYS

The steady-state creep rate of pure aluminium and of four mechanically alloyed aluminium alloys was obtained within more extensive study of the creep behaviour of these materials. Creep data can be rationalized by introducing a threshold stress below which the creep rate is negligible. The estimated threshold stress grows with the increasing content of both carbon and oxygen. Within the threshold stress concept it can be shown that the data are in accord with the natural creep law. The steady-state creep rate can alternatively be described by the equation of thermally activated detachment of dislocations from dispersed particles. A new procedure for evaluation of the relaxation parameter characterizing this process is presented.