Long-time stability of metals after severe plastic deformation: Softening and hardening by self-annealing versus thermal stability

Kaveh Edalati, Yuki Hashiguchi, Hideaki Iwaoka, Hirotaka Matsunaga, Ruslan Z. Valiev, Zenji Horita

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Despite superior properties of ultrafine-grained (UFG) materials processed by severe plastic deformation (SPD), their thermal stability is a concern because of the supersaturated fractions of lattice defects. In this study, the microstructural stability of various UFG materials (2 alloys and 15 pure metals) after SPD processing through the high-pressure torsion (HPT) were investigated at room temperature for up to 10 years. While most of the metals with high melting temperatures remained stable, a softening by self-annealing occurred in pure silver, gold and copper (with moderate melting temperatures), and an unusual hardening occurred in pure magnesium, Al-Zn alloy and Mg-Li alloy (with low melting temperatures). These softening/hardening behaviors by grain coarsening were attributed to the contribution of grain boundaries to dislocation activity or grain-boundary sliding, respectively. It was shown that the self-annealing was accelerated by increasing the processing pressure and strain and by decreasing the processing temperature and stacking fault energy, due to the enhancement of stored energy and/or atomic mobility.

Original languageEnglish
Pages (from-to)340-348
Number of pages9
JournalMaterials Science and Engineering A
Volume729
DOIs
Publication statusPublished - Jun 27 2018

Fingerprint

hardening
softening
plastic deformation
Melting point
Hardening
Plastic deformation
Thermodynamic stability
thermal stability
Metals
Annealing
annealing
melting
Processing
metals
Grain boundary sliding
grain boundaries
Crystal defects
Stacking faults
atomic mobilities
Coarsening

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Long-time stability of metals after severe plastic deformation : Softening and hardening by self-annealing versus thermal stability. / Edalati, Kaveh; Hashiguchi, Yuki; Iwaoka, Hideaki; Matsunaga, Hirotaka; Valiev, Ruslan Z.; Horita, Zenji.

In: Materials Science and Engineering A, Vol. 729, 27.06.2018, p. 340-348.

Research output: Contribution to journalArticle

Edalati, Kaveh ; Hashiguchi, Yuki ; Iwaoka, Hideaki ; Matsunaga, Hirotaka ; Valiev, Ruslan Z. ; Horita, Zenji. / Long-time stability of metals after severe plastic deformation : Softening and hardening by self-annealing versus thermal stability. In: Materials Science and Engineering A. 2018 ; Vol. 729. pp. 340-348.
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