Activated self-propagating high-temperature synthesis of aluminum and titanium nitrides

The paper addresses a possible route for the manufacturing of aluminum and titanium nitride powders by the self-propagating high-temperature synthesis (SHS) method. It was revealed, that a small amount of ammonium chloride NH4Cl additive to the metal powder allows the production of aluminum and titanium nitride powders with a good yield even at a rather low pressure of nitrogen. The influence of NH4Cl amount, metal particle size, porosity of the pressed sample, and nitrogen pressure on the extent of metal conversion into its nitride was experimentally studied. Synthesis of complex nitrides of intermetallics, based on titanium, aluminum and nickel, has also been investigated. Samples were produced by a direct SHS of nickel–aluminum and titanium–aluminum mixtures in a nitrogen atmosphere. Experimental results have shown that during nitridation of Ni–Al and Ti–Al mixtures, respectively, solid solutions of Ni, Al, N and Ti, Al, N correspondingly, are formed, containing mainly the simple nitrides (i.e. TiN and AlN phases), and only small amounts of the stoichiometric ternary complex intermetallic nitrides.