Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates
Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates
The influence of the nanosized rare earth (RE) containing precipitates on grain refinement during severe plastic deformation is investigated in detail through a study of high pressure torsion (HPT) processing of a solution treated and aged Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%). In the early stages of HPT deformation, dislocation generation and pile-up is promoted by the nanosized RE containing β′ precipitates. With increasing strain, the precipitates are cut by the moving dislocations and gradually dissolve into the α-Mg matrix aided by dislocations serving as diffusion channels for solute atoms. After HPT for 2 turns, the hardness reaches a maximum and on further deformation the hardness decreases although the microstructure refinement continues and the dislocation density is increasing. This is due to the continuing dissolution of precipitates, which dominates the hardness evolution at this stage. After HPT for 16 turns, the precipitates have almost completely dissolved and the average grain size is ~33 nm, which is the smallest ever reported for a Mg- or Al-based alloy. The present peak-aged Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%) alloy exhibits quite different microstructure evolution and hardening behaviour during HPT processing as compared to both the cast and the solutionized Mg-Gd-Y-Zn-Zr alloy.
available until June 30, 2018 at authors.elsevier.com/c/1X1XT3HXkRaokD
Mg-RE alloy, High pressure torsion, Precipitates, Microstructure evolution, Work hardening
115–123
Sun, W.T.
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Qiao, X.G.
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Zheng, M.Y.
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He, Y.
ccaae702-0497-4be1-80be-095d248f5907
Hu, Nan
a4341908-c0b2-4821-a126-47a5007f7a88
Xu,, C.
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Gao, N.
9c1370f7-f4a9-4109-8a3a-4089b3baec21
Starink, M.J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
3 June 2018
Sun, W.T.
ad118a36-3179-4b8d-a93f-d30b312954ec
Qiao, X.G.
98a947bc-f5af-4841-9c53-c59a2d3fb9f8
Zheng, M.Y.
dd9a887e-b609-4e63-8ab1-982d5270a252
He, Y.
ccaae702-0497-4be1-80be-095d248f5907
Hu, Nan
a4341908-c0b2-4821-a126-47a5007f7a88
Xu,, C.
142dd97e-cc92-4d6b-9cf0-3e6ec235a1f6
Gao, N.
9c1370f7-f4a9-4109-8a3a-4089b3baec21
Starink, M.J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
Sun, W.T., Qiao, X.G., Zheng, M.Y., He, Y., Hu, Nan, Xu,, C., Gao, N. and Starink, M.J.
(2018)
Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates.
Materials Science and Engineering: A, 728, .
(doi:10.1016/j.msea.2018.05.021).
Abstract
The influence of the nanosized rare earth (RE) containing precipitates on grain refinement during severe plastic deformation is investigated in detail through a study of high pressure torsion (HPT) processing of a solution treated and aged Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%). In the early stages of HPT deformation, dislocation generation and pile-up is promoted by the nanosized RE containing β′ precipitates. With increasing strain, the precipitates are cut by the moving dislocations and gradually dissolve into the α-Mg matrix aided by dislocations serving as diffusion channels for solute atoms. After HPT for 2 turns, the hardness reaches a maximum and on further deformation the hardness decreases although the microstructure refinement continues and the dislocation density is increasing. This is due to the continuing dissolution of precipitates, which dominates the hardness evolution at this stage. After HPT for 16 turns, the precipitates have almost completely dissolved and the average grain size is ~33 nm, which is the smallest ever reported for a Mg- or Al-based alloy. The present peak-aged Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%) alloy exhibits quite different microstructure evolution and hardening behaviour during HPT processing as compared to both the cast and the solutionized Mg-Gd-Y-Zn-Zr alloy.
available until June 30, 2018 at authors.elsevier.com/c/1X1XT3HXkRaokD
Text
Sun et al MSEA2018
- Accepted Manuscript
More information
Accepted/In Press date: 7 May 2018
e-pub ahead of print date: 8 May 2018
Published date: 3 June 2018
Keywords:
Mg-RE alloy, High pressure torsion, Precipitates, Microstructure evolution, Work hardening
Identifiers
Local EPrints ID: 420867
URI: http://eprints.soton.ac.uk/id/eprint/420867
ISSN: 0921-5093
PURE UUID: 1d883f78-5e53-4f58-98dd-69224c88b345
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Date deposited: 17 May 2018 16:30
Last modified: 16 Mar 2024 06:37
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Contributors
Author:
W.T. Sun
Author:
X.G. Qiao
Author:
M.Y. Zheng
Author:
Y. He
Author:
Nan Hu
Author:
C. Xu,
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