Reaction sintering of alumina-aluminide alloys (3A)

A novel pressureless reaction sintering process is presented for the fabrication of Al₂O₃-aluminide alloys (3A). Compacts of intensively milled metal oxide-aluminum mixtures are heat-treated in vacuum or inert atmosphere such that the exothermic reactions take place in a controlled manner essentially at temperatures below the melting point of Al. Dense, homogeneous microstructures were obtained with a variety of Al₂O₃-matrix systems with interpenetrating networks of aluminides of Ti, Fe, Nb, Mo, Zr, Ni, etc. By adding modifiers in the form of oxides or metals, volume and phase composition as well as properties can be tailored in a wide range.