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Controlling the high temperature mechanical behavior of Al alloys by precipitation and severe straining

Controlling the high temperature mechanical behavior of Al alloys by precipitation and severe straining
Controlling the high temperature mechanical behavior of Al alloys by precipitation and severe straining
The aim of this work was to investigate the influence of the precipitate distribution on the microstructure and on the room and high temperature mechanical properties of an age-hardenable aluminium AA6082 alloy following severe straining by high-pressure torsion (HPT). With this goal, specimens in the as-cast and T6 peak-aged conditions were processed by HPT using 0.5, 1 and 5 turns at room temperature. At high strain levels (?>100), similar saturation grain sizes (~250 nm), high-angle boundary fractions (~80%) and hardness values (Hv~160) were obtained for both initial conditions. Grain refinement led to significant strengthening and to good ductility values at room temperature. Analysis by TEM and EDS elemental mapping revealed that HPT processing of the as-cast condition led to fracture of the stable ?-phase into many small precipitates located preferentially along grain boundaries and triple junctions. By contrast, HPT processing of the T6 peak-aged specimens revealed a partial dissolution of the needle-shaped nanoprecipitates. The different evolutions of the precipitate distributions following straining in the as-cast and peak-aged conditions gave rise to dramatic differences in the mechanical properties and the operative deformation mechanisms at warm temperatures. These results provide evidence that the high temperature mechanical behavior of age-hardenable Al alloys may be conveniently controlled by altering the precipitate distribution followed by severe straining.
0921-5093
36-47
Cepeda-Jiménez, C.M.
860325d4-3518-45cb-85d0-2cd15e2f4ba3
Castillo-Rodríguez, M.
91995b06-23db-4de0-a805-647c007993f3
Molina-Aldareguia, J.M.
f4d7ff0d-2b62-4d10-a5dc-9f7acca97064
Huang, Y.
9f4df815-51c1-4ee8-ad63-a92bf997103e
Langdon, T.G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Pérez-Prado, M.T.
41ed62a7-188a-4cb8-94cd-9e5e7495337e
Cepeda-Jiménez, C.M.
860325d4-3518-45cb-85d0-2cd15e2f4ba3
Castillo-Rodríguez, M.
91995b06-23db-4de0-a805-647c007993f3
Molina-Aldareguia, J.M.
f4d7ff0d-2b62-4d10-a5dc-9f7acca97064
Huang, Y.
9f4df815-51c1-4ee8-ad63-a92bf997103e
Langdon, T.G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Pérez-Prado, M.T.
41ed62a7-188a-4cb8-94cd-9e5e7495337e

Cepeda-Jiménez, C.M., Castillo-Rodríguez, M., Molina-Aldareguia, J.M., Huang, Y., Langdon, T.G. and Pérez-Prado, M.T. (2017) Controlling the high temperature mechanical behavior of Al alloys by precipitation and severe straining. Materials Science and Engineering: A, 679, 36-47. (doi:10.1016/j.msea.2016.10.026).

Record type: Article

Abstract

The aim of this work was to investigate the influence of the precipitate distribution on the microstructure and on the room and high temperature mechanical properties of an age-hardenable aluminium AA6082 alloy following severe straining by high-pressure torsion (HPT). With this goal, specimens in the as-cast and T6 peak-aged conditions were processed by HPT using 0.5, 1 and 5 turns at room temperature. At high strain levels (?>100), similar saturation grain sizes (~250 nm), high-angle boundary fractions (~80%) and hardness values (Hv~160) were obtained for both initial conditions. Grain refinement led to significant strengthening and to good ductility values at room temperature. Analysis by TEM and EDS elemental mapping revealed that HPT processing of the as-cast condition led to fracture of the stable ?-phase into many small precipitates located preferentially along grain boundaries and triple junctions. By contrast, HPT processing of the T6 peak-aged specimens revealed a partial dissolution of the needle-shaped nanoprecipitates. The different evolutions of the precipitate distributions following straining in the as-cast and peak-aged conditions gave rise to dramatic differences in the mechanical properties and the operative deformation mechanisms at warm temperatures. These results provide evidence that the high temperature mechanical behavior of age-hardenable Al alloys may be conveniently controlled by altering the precipitate distribution followed by severe straining.

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Accepted/In Press date: 7 October 2016
e-pub ahead of print date: 8 October 2016
Published date: 2 January 2017
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 401329
URI: http://eprints.soton.ac.uk/id/eprint/401329
ISSN: 0921-5093
PURE UUID: 7427a308-c496-4d8b-a507-0668e9be28fd
ORCID for Y. Huang: ORCID iD orcid.org/0000-0001-9259-8123
ORCID for T.G. Langdon: ORCID iD orcid.org/0000-0003-3541-9250

Catalogue record

Date deposited: 14 Oct 2016 16:07
Last modified: 10 Dec 2019 06:23

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