On the dependence of creep-induced dislocation configurations on crystallographic orientation in pure Al and Al Mg

The peak broadening in neutron diffraction experiments on tensile specimens of pure Al (99.8%) and an Al Mg alloy pre-deformed at different creep strains is analysed. These results are combined with the kernel angular misorientation of electron backscatter diffraction data from the creep-deformed microstructures. It is found that differently oriented grains possess different microstrains. These microstrains vary with creep strain in pure Al, but not in the Al Mg alloy. It is proposed that this behaviour can explain the power-law breakdown in pure Al and the large creep strain observed in Al Mg. The present findings further corroborate a description of the creep-induced dislocation structure as a fractal, predicated on previous work.