Morphology and structure effect of Ti additive on the solid-state reaction between Ni and Al powders during mechanical alloying

Abstract

In this study, the mixtures of Ni, Al, and Ti elemental powders with nominal compositions Ni-40at.% Al and Ni-30at.% Al-10at.% Ti were fabricated by mechanically alloying technique. The structural and morphological changes during high-energy mechanical alloying were investigated by X-ray diffraction and scanning electron microscopy. Differences in the kinetics of solid-state reactions which depend on the differences in the individual properties were found. The final products of the mechanical alloying process were nanocrystalline fcc-Ni(Al) and fcc-Ni(Al, Ti) solid solutions with a mean crystallite sizes in the range of a few nanometers. As a result, although the Ti addition was found to accelerate the formation of the solid solution in Ni-Al alloy, it results in a coarser microstructure.