Neutron diffraction stress determination in W-laminates for structural divertor applications

•An innovative multi-layer W–Cu model sample for divertor applications has been non-destructively characterized by means of neutron diffraction measurements.•The average strains and stresses present in the two materials, in the as-brazed state, have been determined with strain accuracies of approximately ±100 µm/m.•Average stress values as low as −17 ± 32 MPa are found through the sample, with some inhomogeneity in the two materials and in the different positions inside the investigated sample.•The experimental procedure developed for this study can be applied to more complex samples, designed for mono-block construction, as well as for in-situ high temperature measurements.

Neutron diffraction measurements have been carried out to develop a non-destructive experimental tool for characterizing the crystallographic structure and the internal stress field in W foil laminates for structural divertor applications in future fusion reactors. The model sample selected for this study had been prepared by brazing, at 1085 °C, 13 W foils with 12 Cu foils. A complete strain distribution measurement through the brazed multilayered specimen and determination of the corresponding stresses has been obtained, assuming zero stress in the through-thickness direction. The average stress determined from the technique across the specimen (over both ‘phases’ of W and Cu) is close to zero at −17 ± 32 MPa, in accordance with the expectations.