Reaction-sintering of intermetallic alloys of the Ni-Al-Mo system

A powder metallurgy route has been used for producing binary and ternary al loys of the Ni-Al-Mo system. Elemental powder mixtures were compacted and, then, sintered in a dilatometer. In this way the dimensional changes involv ed with thermally induced transformations could be followed during continuo us heating runs up to the sintering temperatures. Sintering was assisted by the formation of a liquid phase, promoted by the heat output coming from t he intermetallic phase formation reactions. The amount of liquid phase and the efficiency of sintering was highly dependent on the heating rate. A thr eshold value for optimal densification was identified for some compositions . The effect of other processing parameters, such as pre-sintering compacti on pressure and sintering atmosphere has been considered too. The character isation of the final products was mainly based on X-ray diffraction analyse s. The microstructural parameters and the phase composition of the sintered materials were evaluated. On the basis of these results it is possible to draw some conclusions concerning the main phenomena occurring during the si ntering process. (C) 2000 Elsevier Science Ltd. All rights reserved.