TY  - JOUR
A1  - Fernandez, Ricardo
A1  - Bruno, Giovanni
A1  - Garces, Gerardo
A1  - Nieto-Luis, H.
A1  - Gonzalez-Doncel, Gaspar
T1  - Fractional brownian motion of dislocations during creep deformation of metals
JF  - Materials science & engineering. A, Structural materials
N2  - The present work offers an explanation on how the long-range interaction of dislocations influences their movement, and therefore the strain, during creep of metals. It is proposed that collective motion of dislocations can be described as a fractional Brownian motion. This explains the noisy appearance of the creep strain signal as a function of time. Such signal is split into a deterministic and a stochastic part. These terms can be related to two kinds of dislocation motions: individual and collective, respectively. The description is consistent with the fractal nature of strain-induced dislocation structures predicated in previous works. Moreover, it encompasses the evolution of the strain rate during all stages of creep, including the tertiary one. Creep data from Al99.8% and Al3.85%Mg tested at different temperatures and stresses are used to validate the proposed ideas: it is found that different creep stages present different diffusion characters, and therefore different dislocation motion character.
KW  - Creep
KW  - Aluminum alloys
KW  - Dislocation motion
KW  - Diffusion
KW  - Fractal
KW  - structures
Y1  - 2020
U6  - https://doi.org/10.1016/j.msea.2020.140013
SN  - 0921-5093
SN  - 1873-4936
VL  - 796
PB  - Elsevier
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Serrano-Munoz, Itziar
A1  - Fernández Serrano, Ricardo
A1  - Saliwan-Neumann, Romeo
A1  - Gonzalez-Doncel, Gaspar
A1  - Bruno, Giovanni
T1  - Dislocation substructures in pure aluminium after creep deformation as studied by electron backscatter diffraction
JF  - Journal of applied crystallography / International Union of Crystallography
N2  - 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.
KW  - creep
KW  - pure aluminium
KW  - electron backscatter diffraction (EBSD)
KW  - cellular
KW  - structures
KW  - power law and power-law breakdown
Y1  - 2022
U6  - https://doi.org/10.1107/S1600576722005209
SN  - 1600-5767
VL  - 55
SP  - 860
EP  - 869
PB  - Munksgaard
CY  - Copenhagen
ER  -