Mechano-synthesis and compaction of titanium–titanium nitride composites

Abstract

Abstract Reactive ring grinding was performed on titanium under ammonia and nitrogen atmospheres to form nanostructural precursor powders with varying nitrogen contents. Nitration of Ti during grinding was found to occur more rapidly in N2 than in NH3, however, it was not clear whether this was related to the strong ability of Ti to induce decomposition of molecular nitrogen into reactive atomic species or to the deleterious effect of Fe contamination levels on reactivity of Ti with N. Depending on the amounts of N and Fe present in the precursor powder a range of phases and microstructures could be produced on uniaxial hot pressing at temperatures below the melting point of pure Ti. With increasing N and Fe contents the transition was from α+β type Ti to multi-component microstructures comprising various combinations of nitrogen-rich α-phase, β-Ti, FeTi or TiFe2 and spheroidal particles of titanium nitride (TiN).