Growth, microstructure, and mechanical properties related to modulation period for ZrAlN/ZrB2 superlattice coatings

► ZrAlN/ZrB2 multilayer has potential on quality in protective coatings. ► Modulation period gives a significant contribution to its properties. ► There is a critical modulation period for the hardest multilayer. ► The effects are related to interfacial nature and layer nonacrystalline.