Mechanical properties of HfB2.7 nanocrystalline thin films

The paper describes comparative nanoindentation tests of an HfB 2 single crystal and an HfB 2.7 nanocrystalline thin film deposited on a steel substrate by magnetron sputtering. The boron superstoichiometry and small grain size are shown to result in a significant increase in hardness and decrease of elastic modulus of the thin HfB 2.7 film in comparison to the bulk single crystal. The abnormally high (for inorganic materials) value (87%) of elastic recovery of the impression depth in the thin HfB 2.7 film upon the indenter unloading suggests that the film can be considered as a promising wear-resistant coating.