CREEP OF AL-3WT PERCENT MG AS MEASURED WITH THE INCREMENTAL LOADING METHOD

The deformation behaviour of Al-3wt.%Mg polycrystals was studied in the temperature interval from 295 to 674 K on a creep apparatus, applying the incremental loading method. The temperature dependences of the stresses which first cause plastic strain as well as the stress sensitivities of the strain rate indicate that different deformation mechanisms are operating. At temperatures below 0.5 T(m), the intersection of forest dislocations is the most likely rate-controlling mechanism, superimposed at the lowest applied temperatures by effects of dynamic strain ageing. Above 0.5 T(m) there is diffusion-controlled high-temperature dislocation creep. The differences in results due to the use of the method and its limitations are discussed.