The formation of aluminium nitride boron carbide aluminium composites by wetting assisted infiltration

The possibility of producing aluminium matrixed aluminium nitride-boron carbide composites by pressureless wetting assisted infiltration has been shown. Cold isostatically pressed cup-shaped preforms of boron carbide (1-10 wt%) aluminium nitride mixtures were sintered at 1400-1600 degrees C in nitrogen atmosphere and then infiltrated with aluminium under 6.5 kPa argon at 1250 degrees C. Pore diameter in the preforms increased with increase in sintering temperature. Infiltrated samples which were sectioned and polished showed no infiltration front. Higher B4C contents (4-10%) and sintering temperature (1600 degrees C) resulted in full infiltration. In the sintered preforms AlN was the only phase observed. However, in the infiltrated materials both AlN and Al were observed. (C) 1997 Elsevier Science Limited and Techna S.r.l.