Effect of Pb on the mechanical properties of nanocrystalline Al

Nanocrystalline (nc) Al-Pb two phase mixtures of different Pb concentrations were made by two different routes using high energy ball milling. The microhardness measurements show a softening in nc Al-Pb composites with the increase in Pb content, contradicting the previous results reported in the literature. We conclude that interaction of Pb atoms with nanocrystalline Al grain boundaries is responsible for the softening of the nc Al matrix observed in the current study. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.