Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites

The relative contribution of three strengthening factors in particulate-reinforced metal matrix nanocomposites (MMNCs), namely, load-bearing effect, enhanced dislocation density strengthening effect and Orowan strengthening effect, is evaluated. Orowan strengthening mechanism is found to play a significant role in MMNCs. The relative contribution of Orowan strengthening effect increases with decreasing size of nanoparticles. However, there exists a critical particle size below which the Orowan strengthening effect drops abruptly. The critical particle size, independent of the volume fraction of nanoparticles, is found to be about 5.44 times the magnitude of the Burgers vector of dislocations in the matrix. (c) 2007 Elsevier B.V. All rights reserved.