Reactive sintering of electroless nickel-plated aluminum powders

Fine (about 2 μm) particle size aluminum powders were produced in a plasma reactor, in a flow of argon gas, and the particle size distribution analyzed. A uniformly thick nickel film was deposited on the aluminum powder particles by electroless nickel plating, thus providing more efficient surface contact than can be obtained using conventional methods such as mechanical mixing of nickel and aluminum powder. Nickel-plated aluminum compacts were subsequently sintered at various temperatures in argon and in vacuum, and Ni3Al intermetallic alloys produced. Differential thermal analyses, scanning electron microscopy, and X-ray diffraction analyses of the sintered samples were carried out. Satisfactory densities of 99.8% were achieved by sintering in vacuum at temperatures as low as 680°C.