Creep mechanism in several grades of aluminum at low temperatures

Tetsuya Matsunaga, Eiichi Sato

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Creep tests were performed at less than 0.4 Tm (Tm is the melting temperature) for 99.999%, 99.57%, and 99.52% aluminum with several grain sizes in the range of 50-330 μm. These Al materials show remarkable creep behavior with an apparent activation energy (Q) of 30 kJ/mol, a stress exponent of 4, and a grain-size exponent of zero, and with a larger creep rate with increasing purity. These parameters resemble those of conventional dislocation creep, which is rate-controlled by the usual diffusion processes, except for the extra-low Q value. This means that a non-diffusional process affects the steady state deformation in this temperature region. Transmission electron microscopy revealed the development of a cell structure in the steady state and dislocations without any tangles in the cell interiors. Therefore, because the rate-controlling process could not occur inside of the cells, dislocation annihilation occurred through cross slip around the cell walls. According to these creep parameters and microstructural observations, the observed creep region is suggested to be a new creep region occurring through a non-diffusional process within the existing deformation mechanism map of Al at less than 0.4 Tm.

Original languageEnglish
Pages (from-to)42-48
Number of pages7
JournalKeikinzoku/Journal of Japan Institute of Light Metals
Volume64
Issue number2
DOIs
Publication statusPublished - 2014 Apr 14

Keywords

  • Aluminum
  • Creep
  • Deformation mechanism map
  • Dislocation structure

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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