Nanocrystalline growth and grain-size effects in Au-Cu electrodeposits

The processing-structure-property relationship is investigated for electrodeposited foils of the gold-copper alloy system. A model is presented that relates the deposition process parameters to the nanocrystalline grain size. An activation energy of 1.52 eV atom(-1) for growth is determined for a long-pulse (> 10 msec) mode, and is 0.16 eV atom(-1) for short pulses (< 5 msec). The effect of nanocrystalline grain size on the mechanical properties is assessed using indentation measurements. A Hall-Petch type variation of the Vickers microhardness with nanocrystalline grain size (> 6 nm) is observed for Au-Cu samples with 1-12 wt.% Cu as tested in cross-section. The hardness increases three-fold from a rule-of-mixtures value <1 GPa to a maximum of 2.9 GPa. (c) 2005 Elsevier B.V. All rights reserved.