Fine-grain evolution in friction-stir processed 7050 aluminum

Evolution of the fine-grained structure in friction-stir processed aluminum has been studied using a rotating-tool plunge and extract technique. Initial sizes of newly recrystallized grains are on the order of 25-100 nm. These grains then grow to a size equivalent to that found in friction-stir processed aluminum, 2-5 mum, after heating 1-4 min at 350-450 degreesC. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.