Application of empirical hardness models on hardmetals with alternative binders
Cemented carbides or hardmetals are materials with excellent hardness and toughness. The most widely used composition consists of tungsten carbide (WC) and the metallic binder cobalt (Co). Recent price rises as well as changes in the risk assessment of Co as a hazardous material (EU REACH). This has led to renewed efforts in the search for a suitable substitute and its evaluation. Promising candidates include iron based binders such as iron-nickel-cobalt (FeNiCo). The mechanical properties of cemented carbides are closely correlated with the composition and microstructure. Several empirical models exist for the hardness of WC-Co composites and can be used for tailoring the material properties to the requirements of different applications. In this work hardmetals with various different metal binders have been produced and characterised in respect of their microstructure and hardness. The measured hardness values were compared with the values calculated with different empirical models. Different empirical hardness models exist for WC-Co hardmetals and make it possible to correlate hardness with microstructural parameters. But so far these models have not been applied to cemented carbides with other alternative binder metals such as Ni, Fe or Fe-Ni-Co. This work studies the adaptability of established hardness models for the system WC-Co to hardmetals with alternative binders.