Effect of twin spacing, dislocation density and crystallite size on the strength of nanostructured α-brass

Nanotwinned alpha-brass (Cu-30 wt.% Zn) with varying lamellae thickness in the range of 28-170 nm, has been produced by cryorolling (CR). The effect of CR strain (epsilon(CR) = 0.2-0.95) on the evolution of homogeneity and refinement in terms of twin lamellae thickness, twin spacing, and their distribution, have been studied using high-resolution transmission electron microscopy (HRTEM) and microhardness measurements. Analysis of X-ray peak broadening has shown that the crystallite size reduces down to 20 nm at epsilon(CR) = 0.95, which scales with the subgrain size in preexisting twin lamellae, as revealed under HRTEM. The effect of dislocation density and crystallite size on the strength of nanotwinned brass has been correlated using an analytical model. (C) 2014 Elsevier B.V. All rights reserved.