CHARACTERIZATION OF COMPOSITE OF TIC+TIB2 BONDED WITH NICKEL-BASED BINDER ALLOY - MECHANICAL AND MICROSTRUCTURAL PROPERTIES

Studies of the bonding mechanisms in transition metal 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 + TiB2 composite. An experimental investigation of the selected binder for the TiC + TiB2 composite led to an improvement in densification after sintering, three point bend strength (modulus of rupture values), and identation fracture toughness K(IC) values. Electron probe microanalysis and scanning transmission electron microscopy investigations revealed the segregation of one of the constitutent metal additives in the composites which indicated a need for adjustment of the powder preparation procedures to achieve further improvement in mechanical properties.