Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys
J Schafer and Y Ashkenazy and K Albe and RS Averback, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 546, 307-313 (2012).
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. (C) 2012 Elsevier B.V. All rights reserved.
Return to Publications page