Processing of aluminum nickelides by equal-channel angular extrusion

. Two series of nickel-coated aluminum (Ni + Al) powders were consolidated by equal-channel angular extrusion (ECAE). Mixtures of 78Al-22Ni at.% (63Al-37Ni wt.%) or 39Al-61Ni at.% (23Al-77Ni wt. %) were placed in square-shaped copper blocks, scaled, heated to a range of temperatures from ambient to 700 C, and, once at a uniform temperature, extruded. It was found that the preheating temperature affected the transformation. of the initial Al-Ni composition into aluminum nickelide intermetallics. Scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and microhardness measurements were used to examine the resultant products. The onset and nature of the transformation from the precursors into the products were further studied by differential thermal analysis. These results and the role of ECAE on the transformation are discussed.