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

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.
This project was partially financed by the Spanish MINECO program, corresponding to Project MAT2017-83825-C4-1-R, and by the project Y2018/NMT-4668 Micro-Stress-MAP-C from Comunidad Autónoma de Madrid, Spain.