Elastic grain interaction in electrodeposited nanocomposite Nickel matrix coatings

The effect of SiC and Al2O3 nanoparticles in electrodeposited Nickel coatings was studied by X-ray Diffraction methods, in terms of size and texture of the crystalline domains as well as residual stress and elastic constants. SiC nanoparticles finely disperse and affect grain growth significantly, determining the rise of a strong 100 crystallographic texture with equiaxed domains; whereas Al2O3 nanoparticles tend to agglomerate, only resulting in a precipitation hardening-driven stiffening effect of the metallic matrix. Concerning residual stress analysis, the known elastic grain interaction models seem not suitable to this kind of deposits: a poor modelling of the experimental data is attributed to an inaccurate assessment of the elastic constants and too restrictive hypotheses. More reliable and conclusive results are obtained by an in-situ XRD stress analysis during four point bending, which provides a direct measurement of the effective X-ray elastic constants. The measurement technique is briefly introduced and applied to the electrodeposited Nickel matrix nanocomposite coatings.