STUDY OF MUATI-CARBIDE B_4C-SiC/(Al,Si) REACTION INFILTRATED COMPOSITES BY SEM WITH EBSD

摘要

Characterisation in materials science can be represented by a tetrahedron with the fundamental vertices of composition, properties, processing and applications. In the definition of conceptual developments and design of new materials with singular or unique properties, this characterisation often takes a key role in clarifying what the new material is. B4C has a unique combination of properties that makes it suitable for a wide range of applications in engineering: refractoriness, thermal stability, high hardness with abrasion resistance and low density. However, the low self-diffusion coefficient of B_4C limits full densification in sintering. This constraint was overturned by incorporating metallic alloys in the open structure of the B_4C, or multi-carbide ceramic matrix, thus creating composites strengthened by the metallic phase. Al as a reactive infiltrant of B_4C has a poor wettability below 1000 °C and undesirable reactions occur at higher temperatures. An alternative is alloying Al with other metallic elements such as Si.