Combustion synthesis of boride particle dispersed hard metal from elemental powders

When powder mixtures of iron, aluminum, titanium and boron were heated under pseudo hot isostatic pressure in vacuum to a temperature just above the melting point of aluminum, sudden and rapid temperature rise was always observed, which was due to the exothermic reactions producing FeAl and TiB2. Metallographic investigations revealed that the products consisted of homogeneously dispersed fine hexagonal TiB2 particles and FeAl matrix and that the products included some pores. As the concentrations of titanium and boron in the powder mixture increased, the TiB2 particle size and porosity increased. Both the particle size and the porosity were dramatically reduced by preheating of the powder mixture, which brought about increase in Vickers hardness of the reaction products.