Effect on overall fatigue performance of varying thickness of an intermetallic sublayer within a soft multilayer coating

Abstract

A series of 2IML multilayer coatings (composed of two hard intermetallic (IML) layers and two soft sublayers) with the different thickness of the first IML sublayer have been built to develop our mechanistic understanding of what controls its fatigue performance. Experimental investigations of these multilayer coatings reveal that decreasing the IML-Top layer’s thickness provides improved fatigue resistance. This improvement could be linked to: (1) the increased difficulty of surface crack initiation due to the limitation of the strain ranges experienced at the top surface and (2) the shorter crack propagation period in a thinner IML-Top layer.