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 negli gible. The estimated threshold stress grows with the increasing conten t of both carbon and oxygen. Within the threshold stress concept it ca n be shown that the data are in accord with the natural creep law. The steady-state creep rate can alternatively be described by the equatio n of thermally activated detachment of dislocations from dispersed par ticles. A new procedure for evaluation of the relaxation parameter cha racterizing this process is presented.