Precipitate strengthening and thermal stability in three component metallic nanolaminate thin films

Cu/Ni/Nb tri-layer and CuNi/Nb alloy multilayer films were annealed to examine the microstructural evolution and mechanical properties of three component laminated metallic nanostructures. Scanning transmission electron microscopy showed NixNby compounds forming on either side of the Nb layer in both tri-layer and alloy films. Post annealing nanoindentation showed all annealing conditions resulted in increased hardness, indicative of the NixNby intermetallic phase increasing the hardness of the films. The hardness of both films achieves a maximum hardness after annealing for 3 h at 300 degrees C. The hardness increase as the annealing temperature increases corresponds to a thicker NixNby layer at the incoherent boundary. This strengthening technique could be implemented in a variety of different multilayer systems to achieve age-hardenable multilayer metallic nanostructures.