Grain boundary-assisted resistance to crack propagation in nanoporous gold with fine grains

Abstract

Enhanced resistance to crack propagation in nanoporous gold (np-Au) with fine grains is observed comparing with conventional np-Au with coarse grains. Cyclic hot-rolling is adopted to prepare fine grain structure in Au-Ag precursor alloys, which evolve to fine grained np-Au with grain size of 3.69 mu m after dealloying. Np-Au with fine grains exhibits stable crack growth with enhanced stress intensity for crack propagation K-Jc of 0.133 MPa & BULL;m1/2 while np-Au with coarse grains shows linear elastic fracture behavior with stress intensity factor for crack initiation K-Ic of 0.042 MPa.m(1/2). Enhanced crack resistance in fine grained np-Au is achieved with intergranular fracture, which is attributed to the effective strain energy release through grain boundary plasticity.