Extrusion-Based Additive Manufacturing of WC-10Co Cemented Carbide Produced with Bimodal Ultrafine/Micron WC Particles

Abstract

This article researches the effect of ultrafine (submicron) tungsten carbide powder addition on the microstructure and mechanical properties of WC-10Co cemented carbide produced by the extrusion of a highly filled polymer. This addition aims to develop a material with a good combination of toughness, hardness, and yield strength. The results demonstrate that increasing the ratio between ultrafine and micron WC particles from 0/100 to 45/55 in the initial powder results in successive decreases in average grain size from 2.61 µm to 1.75 µm. When 45% of ultrafine powder is introduced into the mixture, a high number of fine tungsten carbide grains is produced. This promotes inter-grain contact and reduces the free path of the binder phase, which results in a more rigid structure and in the material becoming more brittle. The best mechanical characteristics are achieved in WC-10Co cemented carbide with 15% content of ultrafine powder in the total weight of WC. Here, a microstructure with a bimodal distribution of tungsten carbide grains in a virtually non-intermittent cobalt phase was formed. This allowed us to achieve a compressive strength of 2449 MPa at the deformation of 6.69%, while the modulus of elasticity was 38.8 GPa. The results indicate a good combination of strength and ductility properties in the developed cemented carbide.