REACTION OF COMPACT CARBONITRIDES WITH LIQUID BINDER METALS

In order to gain insight into the metallurgical interactions between t he carbonitrides of the transition metals and binder metals during the liquid phase sintering of cermet cutting tools, contact reactions of liquid nickel and also of nickel/cobalt with compact hot-pressed polyc rystalline Ti(C,N), (Ti,Mo)(C,N), (Ti,W)(C,N) and (Ti,W,Mo,Ta,Nb)(C,N) samples were investigated. It was found that the carbide components o f the carbonitride solid solutions are preferentially dissolved by the liquid metal: to the extent that the reacted zones of the carbonitrid e specimens contained significantly more nitrogen than the bulk carbon itride. This phenomenon is probably due to a dissolution and reprecipi tation process. With the Mo and/or W containing samples higher reactio n rates with the liquid metals were observed, presumably owing to enha nced interactions arising from the presence of readily soluble molybde num and tungsten carbide in the carbonitride solid solution.