on other deposition parameters and most importantly on the substrate temperature the columns may be amorphous or crystalline but at such high deposition rates microcrystalline structure development can be expected at best the difficulty is that the columns provide a mechanically weak structure in which crack propagation can occur uninhibited across the whole thickness of the deposit a special advantage of vacuum deposition technologies is that it is possible to deposit layered materials and thus films possessing exceptional qualities may be produced c f h holleck v schier u201c multilayer pvd coatings for wear protection u201d surface and coatings technology vol 76 77 1995 pp 328 336 layered materials such as superstructures or multilayers are commonly deposited to take advantage of some chemical electronic or optical property of the material as a coating a common example is an antireflective coating on an optical lens it has not been recognized until relatively recently that multilayer coatings may have improved mechanical properties compared with similar coatings made of a single layer the improved mechanical properties may be due to the ability of the interface between the layers to relieve stress this stress relief occurs if the interface provides a slide plane is plastic or may delaminate locally this property of multilayer films has been recognized in regard with their hardness but this recognition has not been translated to other mechanical properties that are significant for metal products that may be used in application where they replace conventional wrought metal parts the process according to the invention can be modified by interrupting film growth at various layers thereby resulting in discontinuous columns that prevent crack propagation across the entire film thickness in this sense it is not necessary that the structure comprise a multiplicity of chemically.