Effect of Initial Surface Quality on Final Roughness and Texture of Annealed Ni-5at.%W Tapes Coated with a Gd₂Zr₂O₇ Buffer Layer

Surface roughness of Ni-5at.%W tapes in coldrolled and annealed conditions after subsequent deposition of a Gd2Zr2O7 buffer layer has been studied as a function of the polishing grade, taking grain boundary grooving into account. It is found that annealing decreases the initial mean surface roughness achieved by mechanical polishing of the cold-rolled material, except after very fine polishing. Furthermore, compared to the surface of the tape annealed after fine polishing, the mean roughness slightly increases after the deposition of the buffer layer. Grain boundary grooving was found to impose a lower limit for the mean surface roughness. In the annealed tapes, the fraction of orientations within 5◦ from the ideal cube orientation was observed to be very sensitive to the surface roughness before annealing.