Neutron Tomography for 3D microstructure mapping of deformation hardened hardmetals used in mining application

Purpose and goal: Feasibility test of using neutron scattering for the composite material cemented carbides.

The aim is to better understand deformation hardening mechanisms in the material. To accomplish this a full penetrating non-destructive analysis of a cemented carbide component by using new neutron scattering techniques is of interest. With new insight of the hardening mechanisms, the cemented carbide material properties can further be optimized.

The project consortium consisted of representatives from MAU, ESS, LU and Sandvik Mining and Rock Solutions. Expected results and effects:

The two diffraction methods showed differences in the variation of the WC lattice parameter as a function of depth. However, it was possible to monitor how the lattice parameter shifts inside the component and therefore see the effect of deformation hardening on the WC phase. Monitoring the binder phase was found to be more difficult.

Both lack of statistics from this phase and difficulties in separating WC and Co peaks was found during the different experiments. To further address this, continued method development of neutron diffraction and tomography is needed and of interest. Approach and implementation:

Neutron diffraction was used to study the strains in the lattice as a function of position inside the sample, which allowed for the hole component. The test matrix consisted of two cemented carbide grades at three different levels of deformation. We tested two different diffraction methods, where time-of-flight diffraction was performed at the instrument TAKUMI at J-PARC, and monochromatic diffraction at the instrument SALSA at Institut Laue Langevin (ILL).

Further, neutron tomography of the binder was of interest and a test run at the instrument IMAT at ISIS, was performed.