Deformation and reconstruction mechanisms in coarse-grained superplastic Al-Mg alloys

W. A. Soer, A. R. Chezan, J. Th. M. De Hosson*

*Corresponding author for this work

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Abstract

This paper concentrates on the superplastic response of fine-grained and coarse-grained Al-Mg alloys under uniaxial tension. To identify the main characteristics of superplastic deformation and to determine the optimum deformation parameters, the microstructure and dislocation substructure of the alloys are analyzed as a function of strain, strain rate and temperature using electron backscatter diffraction and transmission electron microscopy (TEM). Under optimum deformation conditions of temperature and strain rate, these Al-Mg alloys have an elongation to failure in excess of 300%. Dynamic recrystallization is dominant at strain rates in excess of 10(-1) s(-1) and results in a strong coarsening of the microstructure and premature failure. Dynamic recovery prevails at a strain rate of around 10(-2)s(-1), leading to great enhancement of the plasticity of the coarse-grained materials. TEM observations show that subgrain formation proceeds slowly. During initial straining, subgrains are formed primarily along the original grain boundaries. This results in a "core and mantle" microstructure, with dynamic recovery mainly taking place in the mantle region. A uniform substructure is established at a strain of the order of 1. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)3827-3833
Number of pages7
JournalActa Materialia
Volume54
Issue number14
DOIs
Publication statusPublished - Aug-2006

Keywords

  • aluminum alloys
  • superplasticity
  • dynamic recrystallization
  • transmission electron microscopy
  • HIGH-TEMPERATURE DEFORMATION
  • STRAIN RATE SUPERPLASTICITY
  • NUCLEAR-MAGNETIC-RESONANCE
  • MICROSTRUCTURAL EVOLUTION
  • RESTORATION MECHANISMS
  • HOT DEFORMATION
  • CAVITY GROWTH
  • CREEP
  • ALUMINUM
  • RECRYSTALLIZATION

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