Stabilization of ultrafine-grained microstructure in high-purity copper by gas-filled pores produced by severe plastic deformation

Yuanshen Qi*, Anna Kosinova, Askar R. Kilmametov, Boris B. Straumal, Eugen Rabkin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

We observed very high thermal stability (after annealing at 600 °C for 1 h) of the near-surface layers of ultrafine grains in the 99.9995 wt% (5N5) purity Cu processed by high-pressure torsion. We attributed this extraordinary thermal stability of ultrafine-grained microstructure to the nitrogen-filled nano-sized pores that pinned the grain boundaries. Our study reveals that a combination of severe shear strain and surface attrition causes the capture of N2 molecules in the near-surface layer of the deformed metal from the ambient atmosphere. This phenomenon may play an important role in formation of percolating porosity in metals processed by severe plastic deformation.

Original languageEnglish
Pages (from-to)29-33
Number of pages5
JournalScripta Materialia
Volume178
DOIs
StatePublished - 15 Mar 2020

Keywords

  • Copper
  • Electron energy loss spectroscopy (EELS)
  • Grain boundary migration
  • High-pressure torsion
  • Thermal stability

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