Towards understanding of high-temperature deformation mechanisms in Cr-doped hard metals by neutron scattering

Purpose and goal:

Within the project, Sandvik Coromant teamed up with Scatterin AB, Chalmers and KTH with the aim to enhance the mechanistic understanding of the improved properties of hard metals by Cr-doping. To achieve this, in-situ small-angle neutron scattering (SANS) experiments were performed to monitor the WC/Co interface structure evolution and precipitation of secondary carbides at relevant service temperatures.

Furthermore, room temperature neutron diffraction (ND) experiments were performed to quantify residual stresses in bulk specimens. Expected results and effects:

The in-situ SANS experiments provided previously unattainable information on the evolution of microstructure associated with formation, dissolution, and growth of e.g. interfacial layers and larger carbides in hard metals. The ND measurements could reveal the influence of dopants on the residual stresses in hard metals.

This project has not only provided important information on microstructural evolution of Cr-doped hard metals but has also expanded our experience on available sample environments for demanding in-situ SANS experiments. Approach and implementation:

The in-situ SANS experiments was performed on the LARMOR instrument at ISIS Neutron and Muon Source, UK, up to 1000 °C. The SANS experiments were complemented by stress analysis at room temperature using ND on the Engin-X instrument at ISIS. The analysis of reduced ND and SANS data were performed on Scatterin SaaS software.

To complement and validate the neutron scattering results, also lab-scale atom probe tomography (APT) and electron backscatter diffraction (EBSD) investigations were performed.