Ligament size effect in creep of nanoporous gold

Abstract

Spherical nanoindentation creep tests are conducted on four nanoporous gold samples with ligament sizes of 30, 103, 417, and 986 nm. We find the ligament-size dependent creep, increase of total creep strain and creep strain rate with increasing ligament size, in the range of ligament sizes from 103 nm to 986 nm while the most pronounced creep is shown for ligament size of 30 nm. By coating a 2-nm-thick alumina layer on the ligaments, creep increased for ligament sizes ranging from 103 nm to 986 nm, while it decreased for ligament size of 30 nm. The ligament-size dependent creep and effect of surface coating are discussed with dominant dislocation mechanism in the ligaments under the dislocation-mediated creep for each ligament size.