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

Research output: Contribution to journalArticle

18 Citations (Scopus)

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

All Science Journal Classification (ASJC) codes

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

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