Effect of C particle size on the porous formation of TiC particulate locally reinforced steel matrix composites via the SHS reaction of Ni–Ti–C system during casting

Fabrication of steel-matrix composites locally reinforced with in situ TiC particulate using self-propagating high-temperature synthesis (SHS) reactions of 20 wt.% Ni–Ti–C systems with ∼150 μm, ∼38 μm and ∼1 μm C particles during casting has been investigated, respectively. The composites synthesized with ∼38 μm or ∼1 μm C particles consist of TiC and the alloy austenite containing Ni, while the one synthesized with ∼150 μm C particle mainly consists of TiC, the alloy austenite containing Ni and an intermediate phase NiTi. With the increase of C particle size, the porosities of the composites significantly increase. Some large pores exist between the reinforcing region and matrix in the composites synthesized with ∼150 μm and ∼38 μm C particles, respectively, while no large pores are found between that in the composite synthesized with ∼1 μm C particle. As C particle sizes decrease, the hardness and wear resistance of the composites increase.