Stress gradients and grain interaction determination in electrodeposited coatings by synchrotron radiation

Residual stress and texture relationships in galvanic nickel coatings deposited on brass substrates were investigated by synchrotron radiation X-ray diffraction (XRD). The possibility of directly measuring the stress factors by in situ XRD during four-point bending provides a reliable solution to the problem of determining the residual stress state when no a priori assumption can reliably model the elastic constants of the thin film material. The proposed approach is also useful to assess the role of possible texture gradients, and in general to account for property evolutions with the thin film thickness.

► X-ray elastic constants cannot always be easily calculated for textured specimens. ► Experimental measurement is possible by in-situ mechanical testing during diffraction. ► Texture or stress gradient adds complexity to the experimental measurement. ► Different beam energies are used to reach different information depths. ► Example characterisation was performed on a Ni coating on brass.