Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys

Jonathan Schäfer*, Yinon Ashkenazy, Karsten Albe, Robert S. Averback

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The effect of solute segregation on thermal creep in dilute nanocrystalline alloys (Cu-Nb, Cu-Fe, Cu-Zr) was studied at elevated temperatures using molecular dynamics simulations. A combined Monte-Carlo and molecular dynamics simulation technique was first used to equilibrate the distribution of segregating solutes. Then the creep rates of the diluted Cu samples were measured as functions of temperature, composition, load and accumulated strain. In Cu-Nb samples, the creep rates were observed to increase initially with strain, but then saturate at a value close to that obtained for alloys prepared by randomly locating the solute in the grain boundaries. This behavior is attributed to an increase in grain boundary volume and energy with added chemical disorder. At high temperatures, the apparent activation energy for creep was anomalously high, 3. eV, but only 0.3. eV at lower temperatures. This temperature dependence is found to correlate with atomic mobilities in bulk Cu-Nb glasses. Calculations of creep in nanocrystalline Cu alloys containing other solutes, Fe and Zr, show that the suppression of creep rate scales with their atomic volumes when dissolved in Cu.

Original languageAmerican English
Pages (from-to)307-313
Number of pages7
JournalMaterials Science and Engineering: A
Volume546
DOIs
StatePublished - 1 Jun 2012

Bibliographical note

Funding Information:
Financial support for this project was provided by Deutsche Forschungsgemeinschaft through FOR714 . One of us (JS) has been supported by DAAD for his visiting stay at UIUC. Grants of computer time were received from Forschungszentrum Jülich. Research at UIUC was supported by the US Department of Energy, Basic Energy Sciences under grant DEFG02-05ER46217 .

Keywords

  • Creep
  • Grain boundary segregation
  • Grain boundary structure
  • Molecular dynamics
  • Nanocrystalline materials

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