Dislocation substructures in pure aluminium after creep deformation as studied by electron backscatter diffraction

Abstract

In the present work, electron backscatter diffraction is used to investigate the influence of crystal orientation and stress level on the dislocation structures generated during primary and steady-state creep in pure aluminium (99.8%). The goal is to characterize features of the microstructure with a statistically sound approach.

Abstract

In the present work, electron backscatter diffraction was used to determine the microscopic dislocation structures generated during creep (with tests interrupted at the steady state) in pure 99.8% aluminium. This material was investigated at two different stress levels, corresponding to the power-law and power-law breakdown regimes. The results show that the formation of subgrain cellular structures occurs independently of the crystallographic orientation. However, the density of these cellular structures strongly depends on the grain crystallographic orientation with respect to the tensile axis direction, with 〈111〉 grains exhibiting the highest densities at both stress levels. It is proposed that this behaviour is due to the influence of intergranular stresses, which is different in 〈111〉 and 〈001〉 grains.