Significant enhancement in the thermal stability of nanocrystalline metals via immiscible tri-phases

The thermal stability of sputtered Co-Cu-Ag tri-phase immiscible nanocomposites (TPINs) was compared to nanocrystalline Cu50Ag50 and monolithic Cu. After annealing at 973 K, the grain size of Co34Cu33Ag33 was similar to 115 nm, whereas that of Cu50Ag50 increased to over 700 nm. The hardness of annealed Co34Cu33Ag33 TPIN remained high, similar to 3 GPa, comparing to only 1.0 GPa for Cu50Ag50 film. The remarkable thermal stability of the TPIN is largely achieved via the introduction of a third immiscible phase, forming abundant tri-phase triple junctions. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.