A comparison of grain boundary evolution during grain growth in fcc metals

Grain growth of Cu and Ni thin films, subjected to in situ annealing within a transmission electron microscope, has been quantified using a precession-enhanced electron diffraction technique. The orientation of each grain and its misorientation with respect to its neighboring grains were calculated. The Cu underwent grain growth that maintained a monomodal grain size distribution, with its low-angle grain boundaries being consumed, and the Ni exhibited grain size distributions in stages, from monomodal to bimodal to monomodal. The onset of Ni's abnormal grain growth was accompanied by a sharp increase in the Sigma n and Sigma 9 boundary fractions, which is attributed to simulation predictions of their increased mobility. These Sigma 3 and Sigma 9 fractions then dropped to their room temperature values during the third stage of grain growth. In addition to the Sigma 3 and Sigma 9 boundaries, the Sigma 5 and Sigma 7 boundaries also underwent an increase in total boundary fraction with increasing temperature in both metals. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.