Thermal stability of Ni/NiO multilayers

The effects of NiO multilayer additions to pulsed-laser deposited nanocrystalline Ni on the grain growth and texture evolution during annealing have been studied using a combination of in situ annealing in the transmission electron microscope and the recently developed transmission electron backscatter diffraction technique. Grain growth in pure Ni proceeds in an abnormal manner with a small number of grains growing rapidly at the expense of the surrounding nanocrystalline matrix. The addition of NiO layers in the Ni suppressed grain growth and twin formation upon annealing, with increasing oxide content resulting in decreasing extent of grain growth. In pure Ni, the post-annealing texture was found to be composed of a strong {001} texture coupled with the four {122} twin variants from the {001}. With the addition of NiO, annealing twinning, and hence the {122} orientation, was suppressed and instead the final texture was composed of the {001} and {111} orientations.