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

Schäfer, Jonathan and Ashkenazy, Yinon and Albe, Karsten and Averback, Robert S. (2012):
Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys.
In: Materials Science and Engineering A, Elsevier Science Publishing Company, pp. 307-313, 546, (307), [Online-Edition: http://www.sciencedirect.com/science/article/pii/S0921509312...],
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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.

Item Type: Article
Erschienen: 2012
Creators: Schäfer, Jonathan and Ashkenazy, Yinon and Albe, Karsten and Averback, Robert S.
Title: Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys
Language: English
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.

Journal or Publication Title: Materials Science and Engineering A
Volume: 546
Number: 307
Publisher: Elsevier Science Publishing Company
Uncontrolled Keywords: Creep, Nanocrystalline materials, Grain boundary structure, Grain boundary segregation, Molecular dynamics
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Date Deposited: 31 Aug 2012 09:56
Official URL: http://www.sciencedirect.com/science/article/pii/S0921509312...
Identification Number: doi:10.1016/j.msea.2012.03.078
Funders: DFG Al578-7, 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., Research at UIUC was supported by the US Department of Energy, Basic Energy Sciences under grant DEFG02-05ER46217.
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