SOLID-STATE INTERFACIAL REACTIONS IN (Ti,W)C/Ni - AND (Ti,W)C/Co- BASED SYSTEMS

摘要

Hardmetals based on the systems W-C-Co and W-C-Ni are the most important in the field of hardmetal cutting tools. In order to investigate the phase reactions (Ti,W)C/Co and (Ti,W)C/Ni diffusion couples were made. It was found that the reaction zone in (Ti,W)C_(1-x)/Co couples decrease for both stoichiometric and sub-stoichiometric hard phase compositions, if the W content decreases. With Ni as the binder phase in both cases―stoichiometric and sub-stoichiometric―a maximum in the width of the reacted zones was found at [W]/[Ti] = 1. If the hard phases contain nitrogen the reaction with Co is much slower compared to nitrogen-free hard phases. In contact with Ni it was found that the reacted zone is thicker at hard phases with [C]/[N] = 3.2 than [C]/[N] = 2.3 or nitrogen-free hard phases.