Effect of tantalum on the properties and structure of hard alloys based on titanium carbonitride

Abstract

It is determined that the introduction of tantalum (as a carbide) into TiCN−Ni−Mo and TiCN−Ni−Mo—WC hard alloys increases their bending strength, which was evaluated in the milling of steel. It is shown that sintering of the initial mixtures of titanium carbonitride with nickel and molybdenum is followed by the formation of the so-called “K-phase,” which exists mainly in the form of a coating on the TiCN grains. This phase is a complex carbonitride, according to the results of X-ray probe microanalysis (the given structure is referred to as “coaxial” in the literature). It is proposed that the K-phase alone is responsible for the increased strength of titanium-carbonitride-based hard alloys which contain tantalum and have a nickel-molybdenum binder. From this standpoint, it is suggested that pre-made complex tantalum-bearing titanium carbonitride (instead of TiCN) be used as the raw material in hard-alloys production.