Investigation of new aspects in the initial stages of decomposition of Cu2at.%Co with the tomographic atom probe and the field ion microscope

Abstract

AbstractThe initial stages of nucleation and precipitation of the Co‐rich phase in a supersaturated Cu2at.%Co alloy were studied with the field ion microscope (FIM) and the tomographic atom probe (TAP). The specimens of nominal composition Cu2at.%Co were homogenised at 1173 K and aged for different times at different temperatures from 703 to 853 K to follow the decomposition path at these reaction temperatures. In this paper, results on the time evolution of the decomposition are presented. New aspects in the decomposition of CuCo were found, which are discussed. At the initial stages of the nucleation, fluctuations were observed, which could be quantitatively characterised.Decomposition was found to take different paths at different annealing temperatures. At 853 K individual precipitates grew, whereas during coarsening the elastic soft [100] directions were preferred.At 763 K, cigar‐shaped precipitates formed along the [100] directions as a metastable state, which degraded into individual spherical precipitates for longer aging times. The initial stages of decomposition were also characterised for 703 K by using the cluster search algorithm. Copyright © 2007 John Wiley & Sons, Ltd.