Characterisation of composite of TiC + TiB_2 bonded with nickel based binder alloy: mechanical and microstructural properties

摘要

Studies of the bonding mechanisms in transition metals and hardmetals based on transition metals have been conducted to examine the current understanding of the binder-hardmetal interfacial reactions in cemented hardmetals. The studies led to the proposal of a binder selection procedure to be used, in conjunction with thermodynamic and phase equilibria data, for binder selection based on the number of d state electrons in the constituent transition metals. The binder selection procedure developed was used to select a preferred binder composition for a TiC + TiB_2 composite. An experimental investigation of the selected binder for the TiC + TiB_2 composite led to an improvement in densification after sintering, three point bend strength (modulus of rupture values), and indentation fracture toughness K_(IC) values. Electron probe microanalysis and scanning transmission electron microscopy investigations revealed the segregation of one of the constituent metal additives in the composites which indicated a need for adjustment of the powder preparation procedures to achieve further improvement in mechanical properties.