Elastic stress state in superhard multielement coatings

Bending-torsion of the crystal lattice in TiN-based nanocomposite coatings with different microstructures was studied by thin foil electron microscopy. A lattice curvature up to 300 degrees mu m(-1) and internal elastic stress in TiN nanocrystals of size less than 20 nm was found for the first time. The elastic stress states in coatings with nanocrystalline and two-level grain structures were compared. Suppositions were made as to the nature of structural defects responsible for lattice curvature in the coatings with different microstructurcs. The question concerning the nature of superhardness of the coatings was discussed.