Fabrication of Ni3Al thin foil by cold-rolling

Thin foils of stoichiometric Ni3Al with thicknesses ranging from 57 to 315 μm were successfully fabricated by heavily cold-rolling without intermediate annealing. Starting materials were produced by directional solidification using the floating zone method. The total reduction in thickness obtained was as much as 95.5%. This high rolling ductility is considered to be due to the monocrystalline or near monocrystalline form of the starting materials. X-ray pole figures showed the formation of {110} rolling texture. This {110} texture is considered to develop mainly as a result of compressive deformation normal to the rolling plane. The foils recrystallized at temperatures over 1273 K had some tensile ductility (3.0–14.6%) at room temperature in air, in contrast to the usual brittleness of polycrystalline Ni3Al. Electron back scatter diffraction measurements revealed that low angle and Σ3 coincidence site lattice boundaries, which are considered to be crack-resistant, comprised 41–84% of the total grain boundary area in the recrystallized foils. This large fraction is probably a chief cause of the observed ductility. These results demonstrate that it may be possible to utilize Ni3Al thin foils as lightweight, high-temperature structural materials, e.g. honeycomb structures.