Influence of reactant particle size on products of self-propagating high-temperature synthesis in 30 wt.% Cr–Ti–B4C system

Influence of reactant (Cr, Ti and B4C) particle size on the SHS reaction products in 30 wt.% Cr–Ti–B4C system has been investigated. Particle size of Cr powder has a significant effect on the phase compositions and microstructures of SHS reaction products. The SHS reaction in Cr–Ti–B4C system with nano-size Cr goes more complete and occurs more easily than that in the system with micron-size Cr. Increase in particle size of B4C powder has a little effect on the phase compositions of SHS reaction products, which consist of TiB2, TiC and Cr phases as well as transient phase Cr5B3 and a trace of C, but results in the increase of the amount of Cr5B3. Furthermore, the average sizes of TiB2 and TiC increase from ∼0.5 and ∼1 μm to ∼2 and ∼3 μm, respectively, as the B4C particle size increases from ∼3.5 to 40 μm. Increase in particle size of Ti powder (∼38, ∼48 and ∼74 μm) has little influence on the phase compositions of the products, as well as average sizes and morphologies of TiB2 and TiC.