EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Key Words: EBSD; GBCD; DCB; Fracture; Energy; Carbide Boundaries

Cemented carbides (WC-Co) are an important class of tool materials in the manufacturing industry, with applications in mining, drilling and cutting. Their unique composite structure consists of two interpenetrating constituent phases: hard tungsten carbide particles and softer cobalt binder. This results in a unique combination of comparatively high hardness and toughness compared to other hard materials. Yet, performance of WC-Co tools is limited as a result of fracture and wear. In this work, we aim to explore the fracture facet of this problem.

Effect of microstructural features such as boundaries in WC-Co fracture is lacking within current literature. The objective of this work is to first determine WC, grain boundary character distributions (GBCD) for different misorientations (boundary types). Statistically, relative populations of boundary types can be determined from GBCD analysis. This will then be compared with fracture energies of WC boundaries. It is expected that the boundaries with higher energies are likely to be found in lower proportions and the opposite is true for low energy boundaries.

2D electron backscattered diffraction (EBSD) will be used to acquire data for grain boundary statistical analysis as well as choosing boundaries for fracture energy measurements. EBSD data will be processed for GBCD analysis and identify low angle boundaries ideal for fracture energy measurements using custom scripts written in Matlab to work in tandem with MTEX. Finally, a wedge loaded double cantilever beam (DCB) geometry will be employed to determine the fracture energy of WC boundaries such as Σ2 tilt, Σ13a and Σ13b.