Study on the phase diagram of the Ti–B–N system and the interfacial reaction of the Ti/BN joints

The isothermal sections of the Ti–B–N system at different temperatures 1273 K, 1673 K and 1893 K were constructed by extending the related binaries, Ti–B, B–N and Ti–N. The calculated phase diagrams reproduce the latest experimental results well. On the basis of the phase equilibrium calculation, the interfacial reactions and the phase sequences between the two pairs of the diffusion couples, Ti/BN, were analyzed theoretically under the reported experimental conditions of two different couples, the BN plates immersed into a loose Ti powder and the BN particles embedded into a dense Ti matrix at 1273 K. Different phase formation sequences and apparent spatial phase sequences for those two kinds of Ti/BN joints were obtained. It was proved that the different phase sequences of both the phase formation sequences and the apparent spatial phase sequences were dominated by the relative amounts and distribution of the two pairs in the diffusion couples.