Low-temperature creep at ultra-low strain rates in pure aluminum studied by a helicoid spring specimen technique

Junjie Shen, Shigeto Yamasaki, Ken Ichi Ikeda, Satoshi Hata, Hideharu Nakashima

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Abstract

The creep behavior in pure aluminum has been investigated by helicoid spring creep tests at strain rates, ε̇, lower than 10-10 s-1 and low temperature ranging from 0.32Tm to 0.43T m. It was found that the creep behavior in this region depends strongly on grain sizes and impurity concentrations. For high-purity aluminum (5 N Al) with an average grain size, dg > 1600 μm, nearly the wire diameter of the spring sample, where the role of grain boundary during creep deformation can be negligible, the stress exponent was n ∼ 5 and the activation energy was Qc = 32 kJ/mol. Microstructural observation showed the formation of large dislocation cells (∼10μm) and tangled dislocations at the cell walls. For high-purity aluminum (5N Al) with d g = 24 μm, the stress exponent was n ∼ 1 and the activation energy was Qc = 15kJ/mol. On the other hand, for commercial low-purity aluminum (2 N Al) with dg = 25 μm, the stress exponent was n = 2 and the activation energy was Qc = 25 kJ/mol. Microstructural observations revealed dislocations emitted from grain boundaries, those dislocations interacting with intragranular dislocations and the formation of dislocation cells in the grains. Based on those experimental results, the low-temperature creep mechanisms in pure aluminum at ε̇ < 10-10 s-l have been discussed.

Original languageEnglish
Pages (from-to)1381-1387
Number of pages7
JournalMaterials Transactions
Volume52
Issue number7
DOIs
Publication statusPublished - Jul 1 2011

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Aluminum
strain rate
Strain rate
Creep
aluminum
Dislocations (crystals)
Activation energy
purity
exponents
activation energy
Grain boundaries
Temperature
grain boundaries
grain size
creep tests
cells
Cells
Wire
Impurities
wire

All Science Journal Classification (ASJC) codes

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

Cite this

Low-temperature creep at ultra-low strain rates in pure aluminum studied by a helicoid spring specimen technique. / Shen, Junjie; Yamasaki, Shigeto; Ikeda, Ken Ichi; Hata, Satoshi; Nakashima, Hideharu.

In: Materials Transactions, Vol. 52, No. 7, 01.07.2011, p. 1381-1387.

Research output: Contribution to journalArticle

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