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Mechanical properties of an Al-Zn-Mg alloy processed by ECAP and heat treatments

Mechanical properties of an Al-Zn-Mg alloy processed by ECAP and heat treatments
Mechanical properties of an Al-Zn-Mg alloy processed by ECAP and heat treatments
An investigation was conducted to study the influence of equal-channel angular pressing (ECAP) and post-ECAP aging at 393 K for 20 h on the microstructures and tensile properties of a supersaturated Al-Zn-Mg alloy together with the effect of pre-ECAP heat treatments on the mechanical properties of the alloy after ECAP and after post-ECAP heat treatments. The results show that during ECAP processing for up to 4 passes for the supersaturated Al alloy there is a simultaneous occurrence of grain refinement, increases in the dislocation density and dynamic aging precipitation forming large numbers of fine spherical well-distributed precipitates which enhance the yield strength but decrease the ductility. During post-ECAP aging, there is a limited dislocation recovery with slight grain growth and the precipitate sizes increase together with the formation of a few larger platelet precipitates and the transformation of G.P. zones to η' and η' to η leading to a strength reduction after 4 passes of ECAP. The precipitates in the ECAP-processed alloy with pre-ECAP in the supersaturated state formed through dynamic aging precipitation are higher in their volume fraction, smaller in their size and more homogeneously distributed in the Al matrix than those in the alloy with pre-ECAP in the peak aging state which mainly come from the fragmented η' existing in the matrix before ECAP. The strengths of the alloy both after ECAP processing and after post-ECAP heat treatments with pre-ECAP in the supersaturation state are higher than with pre-ECAP in the peak aging state.
0925-8388
631-639
Afifi, Mohamed A.
1becb81a-3778-40ea-bb51-162e3535524d
Wang, Ying Chun
5c067a6f-de5d-4fcb-9b0d-80a42c3634b0
Pereira, Pedro H.R.
9ee129fd-0e06-482d-990c-971aaf83b1d0
Huang, Yi
9f4df815-51c1-4ee8-ad63-a92bf997103e
Wang, Yangwei
41f5818d-dad8-41e4-9688-a37ad49bac83
Cheng, Xingwang
a6620e1f-2f98-42b8-a683-29b5bd2920d1
Li, Shukui
19c3a610-ebf7-43e3-b13a-2cf61a219d0b
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Afifi, Mohamed A.
1becb81a-3778-40ea-bb51-162e3535524d
Wang, Ying Chun
5c067a6f-de5d-4fcb-9b0d-80a42c3634b0
Pereira, Pedro H.R.
9ee129fd-0e06-482d-990c-971aaf83b1d0
Huang, Yi
9f4df815-51c1-4ee8-ad63-a92bf997103e
Wang, Yangwei
41f5818d-dad8-41e4-9688-a37ad49bac83
Cheng, Xingwang
a6620e1f-2f98-42b8-a683-29b5bd2920d1
Li, Shukui
19c3a610-ebf7-43e3-b13a-2cf61a219d0b
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86

Afifi, Mohamed A., Wang, Ying Chun, Pereira, Pedro H.R., Huang, Yi, Wang, Yangwei, Cheng, Xingwang, Li, Shukui and Langdon, Terence G. (2018) Mechanical properties of an Al-Zn-Mg alloy processed by ECAP and heat treatments. Journal of Alloys and Compounds, 769, 631-639. (doi:10.1016/j.jallcom.2018.07.343).

Record type: Article

Abstract

An investigation was conducted to study the influence of equal-channel angular pressing (ECAP) and post-ECAP aging at 393 K for 20 h on the microstructures and tensile properties of a supersaturated Al-Zn-Mg alloy together with the effect of pre-ECAP heat treatments on the mechanical properties of the alloy after ECAP and after post-ECAP heat treatments. The results show that during ECAP processing for up to 4 passes for the supersaturated Al alloy there is a simultaneous occurrence of grain refinement, increases in the dislocation density and dynamic aging precipitation forming large numbers of fine spherical well-distributed precipitates which enhance the yield strength but decrease the ductility. During post-ECAP aging, there is a limited dislocation recovery with slight grain growth and the precipitate sizes increase together with the formation of a few larger platelet precipitates and the transformation of G.P. zones to η' and η' to η leading to a strength reduction after 4 passes of ECAP. The precipitates in the ECAP-processed alloy with pre-ECAP in the supersaturated state formed through dynamic aging precipitation are higher in their volume fraction, smaller in their size and more homogeneously distributed in the Al matrix than those in the alloy with pre-ECAP in the peak aging state which mainly come from the fragmented η' existing in the matrix before ECAP. The strengths of the alloy both after ECAP processing and after post-ECAP heat treatments with pre-ECAP in the supersaturation state are higher than with pre-ECAP in the peak aging state.

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Afifi-JAC 2018-accepted manuscript - Accepted Manuscript
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Accepted/In Press date: 30 July 2018
e-pub ahead of print date: 3 August 2018
Published date: 15 November 2018

Identifiers

Local EPrints ID: 422865
URI: http://eprints.soton.ac.uk/id/eprint/422865
ISSN: 0925-8388
PURE UUID: 6a6e59fd-6c4c-4b5c-8627-9108c73f00d2
ORCID for Yi Huang: ORCID iD orcid.org/0000-0001-9259-8123
ORCID for Terence G. Langdon: ORCID iD orcid.org/0000-0003-3541-9250

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Date deposited: 07 Aug 2018 16:30
Last modified: 17 Dec 2019 05:17

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Contributors

Author: Mohamed A. Afifi
Author: Ying Chun Wang
Author: Pedro H.R. Pereira
Author: Yi Huang ORCID iD
Author: Yangwei Wang
Author: Xingwang Cheng
Author: Shukui Li

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