Grain growth and texture changes in a Ni foil during diffusion bonding to ZrO2

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Abstract
We have studied the changes in microstructure which occur in a Ni foil when it is diffusion bonded to cubic ZrO2. The foil undergoes a change in preferred orientation during bonding to produce a texture distinctly different from that found in a foil annealed in vacuum. The rate of grain growth in the Ni is significantly faster during diffusion bonding than is found during annealing a foil under the same conditions. It can be argued that the different texture occurs because the Ni-ZrO2 interface has a lower energy when the Ni(111) plane is parallel to the interface. This is consistent with the fact that the (111) face is a lowest-energy interface in other metal-ceramic systems. However, there is no clear expanation for the more rapid grain growth kinetics which may occur because of the difference in driving force, the absence of thermal grooving in the Ni foil when bonded, or a supersaturation of point defects in the Ni foil during diffusion bonding.