Significance of homologous temperature in softening behavior and grain size of pure metals processed by high-pressure torsion

Kaveh Edalati, Zenji Horita

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108 Citations (Scopus)


High purity metals with low melting temperatures such as indium (99.999%), tin (99.9%), lead (99%), zinc (99.99%) and aluminum (99.99%) were processed using high-pressure torsion (HPT). An unusual softening behavior was observed in all these metals after processing by HPT at room temperature. Pure copper (99.99%) and palladium (99.95%) were used to simulate the softening behavior due to a thermal effect by processing and subsequently holding at the temperatures equivalent to room temperature of pure Al. It is shown that a hardness peak appears in any metal by static softening after processing by HPT at a homologous temperature of 0.32 which is equivalent to room temperature of pure Al. The contribution of dynamic softening on hardness decrease becomes more important as the homologous temperature and stacking fault energy increase. Microstructural examinations indicate that, although the stacking fault energy influences the rate of the microstructural evolution, the homologous temperature appears to be a dominant parameter to determine the steady-state grain size after processing by HPT.

Original languageEnglish
Pages (from-to)7514-7523
Number of pages10
JournalMaterials Science and Engineering A
Issue number25-26
Publication statusPublished - Sep 25 2011


All Science Journal Classification (ASJC) codes

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

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