Abstract:TiC-TiB₂-NiAl composites were fabricated by self-propagating high temperature reaction synthesis(SHS) with Ti, B₄C, Ni and Al powders as raw materials. The effects of NiAl content on phase constituents and microstructures were investigated. The results show that the reaction products are composed of TiB₂, TiC and NiAl. The content of NiAl increases with the adding of Ni+Al in green compacts. TiB₂, TiC and NiAl grains present in different shapes in the matrix, TiB₂ being in hexagonal or rectangular shapes, TiC in spherical shapes, and NiAl squeezed into the gaps of TiC and TiB₂ grains. With the increase of NiAl content, the grains of TiC-TiB₂-NiAl composites are refined, their density and compressive strength are improved, and the shapes of TiC grains become spherical instead of irregular ones. Finally, the fracture mechanism of the composites transforms from intergranular fracture mode to the compounded fracture mode of intergranular fracture and transgranular fracture.

Key words: TiC-TiB₂-NiAl; self-propagating high temperature reaction synthesis (SHS); composites; microstructure