Effects of tungsten and aluminum additions on the formation of molybdenum disilicide by mechanically-induced self-propagating reaction

Abstract

Abstract The effects of tungsten and aluminum additions to Mo–Si system on the formation of MoSi 2 by mechanically-induced self-propagating reaction in a high-energy ball mill were investigated by X-ray diffraction. The incubation time for mechanically-induced self-propagating reaction to form MoSi 2 was 90 min in Mo–Si system. With the addition of tungsten to Mo–Si system, the incubation time of mechanically-induced self-propagating reaction of (W x ,Mo 1− x )Si 2 system was prolonged. It was due to the decrease of adiabatic temperature with increase in x , and the mechanically-induced self-propagating reaction was not observed until 150 min of high-energy milling in (W x ,Mo 1− x )Si 2 powder sample with x equals to 0.4. Conversely, the minor aluminum ( y 1− y ,Al y ) 2 system) substituting for silicon had shorten the incubation period and accelerated the reaction. When tungsten and aluminium were added simultaneously to Mo–Si system, the mechanically-induced self-propagating reaction was observed in (W 0.1 ,Mo 0.9 )(Si 0.9 ,Al 0.1 ) 2 sample, but it was not observed in (W 0.2 ,Mo 0.8 )(Si 0.8 ,Al 0.2 ) 2 and (W 0.3 ,Mo 0.7 )(Si 0.7 ,Al 0.3 ) 2 samples.