Reactive processing of nanostructured nickel aluminide intermetallics starting from elemental nanopowders

The current paper investigates the fabrication of nanostructured intermetallic alloys Ni3Al starting from elemental nanopowders Ni and Al micro-alloyed with different compositions of submicron B and Nb metal powders. Low-energy reaction synthesis (RS) of the nanopowder greenʹs compact in an air furnace was successfully carried out from which a nanostructured micro-alloyed Ni3Al alloy was successfully produced. The nanopowders were completely reacted to form the intended single-phase nanostructured Ni3Al with no remaining nanopowders up to 0.3 and 4 wt% compositions of B and Nb, respectively, with a maximum relative density of 90%. Microstructure examination revealed that the micro-alloyed Ni3Al alloys produced contain very fine grain structures (120–140 nm) which resulted in an almost 200% increase in the microhardness, as well as a considerable increase in the final product ductility as a result of small micro-alloying additions of B (0.1 wt%) and Nb (up to 4 wt%). Both SEM/EDS analysis and XRD were used to examine the phase compositions after the in situ reactive processing.