TY - JOUR
T1 - A combined approach to microstructure mapping of an Al-Li AA2199 friction stir weld
AU - Steuwer, A.
AU - Dumont, M.
AU - Altenkirch, J.
AU - Birosca, S.
AU - Deschamps, A.
AU - Prangnell, P. B.
AU - Withers, P. J.
PY - 2011/5
Y1 - 2011/5
N2 - A wide range of complementary techniques are used to build up a detailed picture of the microstructural zones found in friction stir welds (FSW) in an advanced AA2199 Al-Li alloy. Neutron and synchrotron X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, small angle X-ray scattering, scanning electron microscopy, electron backscatter diffraction (EBSD) and hardness mapping are brought together to build up a detailed two-dimensional picture of the grain morphology, precipitate type, size, volume fraction and matrix solute content across the weld cross section and to explain the general lack of a W-shaped hardness profile across FSW in third-generation Al-Li-Cu-Mg alloys. Dissolution of the age-hardening phases occurred in different regions of the weld, depending on their respective solvus temperatures, with δ′ dissolving within the heat-affected zone and T1 coarsening in the thermo-mechanically affected zone before going into solution in the weld nugget. Changes to the precipitate distribution, and especially to the T1 phase, are linked to a significant reduction in hardness (strength) and unstrained lattice parameter across the weld zone. It was also possible to show that the low recovery of nugget zone hardness is primarily due to its poor natural ageing response.
AB - A wide range of complementary techniques are used to build up a detailed picture of the microstructural zones found in friction stir welds (FSW) in an advanced AA2199 Al-Li alloy. Neutron and synchrotron X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, small angle X-ray scattering, scanning electron microscopy, electron backscatter diffraction (EBSD) and hardness mapping are brought together to build up a detailed two-dimensional picture of the grain morphology, precipitate type, size, volume fraction and matrix solute content across the weld cross section and to explain the general lack of a W-shaped hardness profile across FSW in third-generation Al-Li-Cu-Mg alloys. Dissolution of the age-hardening phases occurred in different regions of the weld, depending on their respective solvus temperatures, with δ′ dissolving within the heat-affected zone and T1 coarsening in the thermo-mechanically affected zone before going into solution in the weld nugget. Changes to the precipitate distribution, and especially to the T1 phase, are linked to a significant reduction in hardness (strength) and unstrained lattice parameter across the weld zone. It was also possible to show that the low recovery of nugget zone hardness is primarily due to its poor natural ageing response.
KW - Aluminium alloys
KW - Friction stir welding
KW - Neutron diffraction
KW - Small angle synchrotron X-ray scattering
KW - Synchrotron radiation
UR - http://www.scopus.com/inward/record.url?scp=79953175004&partnerID=8YFLogxK
UR - https://www.sciencedirect.com/journal/acta-materialia/vol/59/issue/8
U2 - 10.1016/j.actamat.2011.01.040
DO - 10.1016/j.actamat.2011.01.040
M3 - Article
AN - SCOPUS:79953175004
SN - 1359-6454
VL - 59
SP - 3002
EP - 3011
JO - Acta Materialia
JF - Acta Materialia
IS - 8
ER -