Hui Chang

By Zhenhua Dan, Fengxiang Qin, Izumi Muto, Nobuyoshi Hara and Hui Chang

Au-group (Ag, Au) and Pt-group (Ni, Pd, Pt) metals have lower surface diffusion coefficients than Cu and are defined as LSD. The chemical composition has been designed based on the differences in diffusion coefficients, and the micro-alloying of 1 at % LSD metals with the Ti60Cu40 amorphous precursor alloy results in the formation of bi-continuous nanoporous copper (NPC) with finer nanoporous structure. LSD-stabilized NPCs have the smallest characteristic pore sizes of 7 nm and 6 nm after dealloying amorphous Ti60Cu39Pd1 and Ti60Cu39Pt1 precursor alloys, while NPC had a pore size of 39 nm after dealloying the amorphous Ti60Cu40 alloy. The refining factor increases approximately from 3.7 for Ti60Cu39Ag1 to 1780 for Ti60Cu39Pt1 precursors due to the dramatic decrease in the surface diffusivity during both preferential dissolution and rearrangement of Cu adatoms. The elaboration efficiencies of Ti60Cu40 alloy with addition of 1 at.% Pt-group elements are higher than those of Au-group elements. The homogeneous distribution of LSD elements in both the precursors and final stabilized NPCs played a key role in restriction of the long-distance diffusion of Cu adatoms. LSD-stabilized NPCs are able to have an ultrafine nanoporosity with a pore size almost one order smaller than that from LSD-free alloys.

Part of the book: New Uses of Micro and Nanomaterials