Low temperature processing of reaction-bonded boron carbide composites

The present paper is concerned with the fabrication of fully dense B ₄C-Mg, B₄C-AZ91 alloy, and B₄C-Mg,Si (eutectic) composites at a significantly lower (750-1000°C) temperature range. The key feature of the novel approach is based on the Mg-vapor atmosphere, under which the infiltration process is carried out. This approach has also been used to fabricate B₄C-Al composites at a low temperature. The microstructure and the mechanical properties of the composites are described and discussed. It was concluded that the formation of the deleterious aluminum carbide (Al ₄C₃) depends on the presence of free carbon in the boron carbide powders. The suggested approach for low temperature fabrication of reaction bonded composites under Mg vapor can be further expanded to other boride and carbide phases. A novel approach for fabrication of reaction bonded B₄C-(Al, Mg) composites at low temperature is described. The key feature of this approach is the uses of Mg-vapor atmosphere during the infiltration process. Low temperature process allows preventingthe formation of the deleterious aluminum carbide (Al₄C₃).