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

摘要

The reaction process of combustion synthesis for TiB2-Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （XRD） analysis, SEM analysis and differential thermal analysis （DTA）. The XRD analysis results for the different parts of the quenched specimen show that TiCux intermetallic phase firstly forms with the propagation of combustion wave, and then Ti 1.87 B 50 and Ti3B4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB2 phase forms because of the continuous diffusion of B atoms. The formation of TiB2 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 TiCux, TiBx intermetallic phases; large numbers of TiCux intermetallic phases formation and some fine TiB2 particles precipitation; and the TiB2 particles coarsening and the stable TiB2 and Cu two phases formation in the final product.