Stabilization of Nanocrystalline Copper by Tantalum Grain Boundary Segregation

Nanocrystalline Cu-Ta alloy films were deposited on glass slides by magnetron sputtering. Microstructure characterization proved that most of the tantalum atoms are segregated in the grain boundaries. Nanoindentation creep measurements were performed on it to uncover the stability mechanism of grain boundary segregation on nanocrystalline materials. It is found that segregation can effectively slow down the creep strain rate and the grain boundary activities. The suppressed grain boundary activities endow the alloy with a stable microstructure during plastic deformation and annealing.