Pulsed electron-beam treatment of WC-TiC-Co hard-alloy cutting tools: wearresistance and microstructural evolution

The mechanisms for changes in the structure-phase state, microhardness, and wear resistance have been investigated for carbide inserts made of type T1 5K6 (WC-15TiC-6Co)hard alloy, irradiated with a low-energy (20-30keV, high- current (similar to 10(2) A cm(-2)) electron beam of duration 2.5 mu s. Usi ng transmission electron microscopy, it has been established that the pulse d melting of the near-surface (similar to 1 mu m) layer results in the form ation of a subgrain structure in the binding phase, segregation of nanosize d carbide particles in the near-boundary regions, and the allotropic transf ormation of WC. The irradiation increases by about three times the durabili ty of the inserts at elevated cutting rates for steels. The increase in dur ability is associated with the efficient hardening of the Co binder immedia tely on irradiation and with its high thermal stability being retained in t he process of cutting due to the stability of the dislocation substructure provided by second-phase segregates. (C) 2000 Elsevier Science S.A. All rig hts reserved.