Pressure un-assisted reactive powder processing of high-density aluminide composites

The combustion synthesis of aluminide intermetallic composites has been extensively studied during the past three decades. A major problem in the combustion synthesis of intermetallic composites has been poor density and poor homogeneity of the final product. This has resulted in the need for the application of pressure to densify the product in addition to high temperature heat treatments to homogenize it. This paper discusses a new strategy for elemental green compact design that promotes considerably improved densities of combustion synthesized nickel aluminide–titanium carbide composites (at 20 vol.% TiC loading) without the application of external pressures. The paper covers ball milling studies, compaction behavior and the effect of elemental powder/green compact microstructural design on the porosity, phase content, microstructure and hardness of the combustion synthesized product. Product porosities as low as 1.4% have been produced using this new design compared to 25% using conventional means of powder processing prior to combustion synthesis, this has also contributed to a greater than five times improvement in hardness of the resulting product.