Hardening by annealing and implementation of high ductility of ultra-fine grained aluminum

Experiment and theory

T. S. Orlova, N. V. Skiba, A. M. Mavlyutov, M. Y. Murashkin, R. Z. Valiev, M. Y. Gutkin

Research outputpeer-review

3 Citations (Scopus)

Abstract

The influence of low temperature annealing and subsequent deformation on microstructure, strength and ductility was investigated for the first time for high pressure torsion (HPT) processed commercially pure Al. Extremely high increases in the conventional yield stress (up to 50%) and ultimate tensile strength (up to 30%) were obtained by annealing of the ultrafine grained (UFG) samples in the range 90–200 °C for 1 h. Such increases were accompanied by a sharp drop in ductility up to 1%. Implementation of high ductility at the level of coarse-grained Al, while maintaining high strength of the HPT-processed sample was demonstrated for the first time and achieved by repeating the low temperature annealing followed by subsequent additional HPT deformation. The key role of relaxation of non-equilibrium high-angle grain boundaries (GBs) in the strengthening effect of UFG-Al by annealing is shown. Two theoretical models are suggested to explain the hardening by annealing and the implementation of high ductility in UFG structures. Within the models, plastic deformation occurs through emission of lattice dislocations from triple junctions of GBs containing pile-ups of grain-boundary dislocations, glide of the lattice dislocations across neighboring grains, their accumulation at and climb along the opposite GBs. The energy characteristics and the critical stresses of dislocation emission are determined in two different cases, for UFG Al subjected to annealing only and to annealing with subsequent additional HPT deformation. The calculated theoretical dependences of the flow stress on the plastic deformation value well fit qualitatively and quantitatively to our experimental data.

Original languageEnglish
Pages (from-to)224-240
Number of pages17
JournalReviews on Advanced Materials Science
Volume57
Issue number2
DOIs
Publication statusPublished - 1 Jan 2018

Fingerprint

Aluminum
ductility
hardening
Ductility
Hardening
Annealing
aluminum
annealing
Torsional stress
torsion
Grain boundaries
grain boundaries
Dislocations (crystals)
Experiments
Crystal lattices
plastic deformation
Plastic deformation
critical loading
Strengthening (metal)
piles

Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

Cite this

@article{f8ea1ea8c3234dc6977f058ad11bab67,
title = "Hardening by annealing and implementation of high ductility of ultra-fine grained aluminum: Experiment and theory",
abstract = "The influence of low temperature annealing and subsequent deformation on microstructure, strength and ductility was investigated for the first time for high pressure torsion (HPT) processed commercially pure Al. Extremely high increases in the conventional yield stress (up to 50{\%}) and ultimate tensile strength (up to 30{\%}) were obtained by annealing of the ultrafine grained (UFG) samples in the range 90–200 °C for 1 h. Such increases were accompanied by a sharp drop in ductility up to 1{\%}. Implementation of high ductility at the level of coarse-grained Al, while maintaining high strength of the HPT-processed sample was demonstrated for the first time and achieved by repeating the low temperature annealing followed by subsequent additional HPT deformation. The key role of relaxation of non-equilibrium high-angle grain boundaries (GBs) in the strengthening effect of UFG-Al by annealing is shown. Two theoretical models are suggested to explain the hardening by annealing and the implementation of high ductility in UFG structures. Within the models, plastic deformation occurs through emission of lattice dislocations from triple junctions of GBs containing pile-ups of grain-boundary dislocations, glide of the lattice dislocations across neighboring grains, their accumulation at and climb along the opposite GBs. The energy characteristics and the critical stresses of dislocation emission are determined in two different cases, for UFG Al subjected to annealing only and to annealing with subsequent additional HPT deformation. The calculated theoretical dependences of the flow stress on the plastic deformation value well fit qualitatively and quantitatively to our experimental data.",
author = "Orlova, {T. S.} and Skiba, {N. V.} and Mavlyutov, {A. M.} and Murashkin, {M. Y.} and Valiev, {R. Z.} and Gutkin, {M. Y.}",
year = "2018",
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language = "English",
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Hardening by annealing and implementation of high ductility of ultra-fine grained aluminum : Experiment and theory. / Orlova, T. S.; Skiba, N. V.; Mavlyutov, A. M.; Murashkin, M. Y.; Valiev, R. Z.; Gutkin, M. Y.

In: Reviews on Advanced Materials Science, Vol. 57, No. 2, 01.01.2018, p. 224-240.

Research outputpeer-review

TY - JOUR

T1 - Hardening by annealing and implementation of high ductility of ultra-fine grained aluminum

T2 - Experiment and theory

AU - Orlova, T. S.

AU - Skiba, N. V.

AU - Mavlyutov, A. M.

AU - Murashkin, M. Y.

AU - Valiev, R. Z.

AU - Gutkin, M. Y.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - The influence of low temperature annealing and subsequent deformation on microstructure, strength and ductility was investigated for the first time for high pressure torsion (HPT) processed commercially pure Al. Extremely high increases in the conventional yield stress (up to 50%) and ultimate tensile strength (up to 30%) were obtained by annealing of the ultrafine grained (UFG) samples in the range 90–200 °C for 1 h. Such increases were accompanied by a sharp drop in ductility up to 1%. Implementation of high ductility at the level of coarse-grained Al, while maintaining high strength of the HPT-processed sample was demonstrated for the first time and achieved by repeating the low temperature annealing followed by subsequent additional HPT deformation. The key role of relaxation of non-equilibrium high-angle grain boundaries (GBs) in the strengthening effect of UFG-Al by annealing is shown. Two theoretical models are suggested to explain the hardening by annealing and the implementation of high ductility in UFG structures. Within the models, plastic deformation occurs through emission of lattice dislocations from triple junctions of GBs containing pile-ups of grain-boundary dislocations, glide of the lattice dislocations across neighboring grains, their accumulation at and climb along the opposite GBs. The energy characteristics and the critical stresses of dislocation emission are determined in two different cases, for UFG Al subjected to annealing only and to annealing with subsequent additional HPT deformation. The calculated theoretical dependences of the flow stress on the plastic deformation value well fit qualitatively and quantitatively to our experimental data.

AB - The influence of low temperature annealing and subsequent deformation on microstructure, strength and ductility was investigated for the first time for high pressure torsion (HPT) processed commercially pure Al. Extremely high increases in the conventional yield stress (up to 50%) and ultimate tensile strength (up to 30%) were obtained by annealing of the ultrafine grained (UFG) samples in the range 90–200 °C for 1 h. Such increases were accompanied by a sharp drop in ductility up to 1%. Implementation of high ductility at the level of coarse-grained Al, while maintaining high strength of the HPT-processed sample was demonstrated for the first time and achieved by repeating the low temperature annealing followed by subsequent additional HPT deformation. The key role of relaxation of non-equilibrium high-angle grain boundaries (GBs) in the strengthening effect of UFG-Al by annealing is shown. Two theoretical models are suggested to explain the hardening by annealing and the implementation of high ductility in UFG structures. Within the models, plastic deformation occurs through emission of lattice dislocations from triple junctions of GBs containing pile-ups of grain-boundary dislocations, glide of the lattice dislocations across neighboring grains, their accumulation at and climb along the opposite GBs. The energy characteristics and the critical stresses of dislocation emission are determined in two different cases, for UFG Al subjected to annealing only and to annealing with subsequent additional HPT deformation. The calculated theoretical dependences of the flow stress on the plastic deformation value well fit qualitatively and quantitatively to our experimental data.

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SN - 1606-5131

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ER -