The Process of TiB_2-Cu Composite Phase and Structure Formation during Combustion Synthesis

摘要

The reaction process of combustion synthesis for TiB_2-Cu was investigated in detail using combustion-wave wresting experiment, X-ray diffraction (XPD) analysis, SEM analysis and differential thermal analysis ( DTA) . The XRD analysis results for the different parts of the quenched specimen show that TiCu_x inter-metallic phase firstly forms with the propagation of combustion wave, and then T_(1.87)B_(50) and Ti_3 B_4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB_2 phase forms because of the continuous diffusion of B atoms . The formation of TiB_2 phase is not completed by one step, but undergoes several transient processes. The process of reaction synthesis for Ti-B-Cu ternary system can be divided into three main stages: melting of Cu and Ti, and the formation of Cu-Ti melt and few TiCu_x, TiB_x intermetallic phases; large numbers of TiCu_x intermetallic phases formation and some fine TiB_2 particles precipitation; and the TiB_2 particles coarsening and the stable TiB_2 and, Cu two phases formation in the final product.