Residual stress measurement of {112}-oriented CrN layers in CrN/Cr multilayer films

In this work, the authors propose and verify a method of measuring the residual stress of {112}-oriented chromium nitride (CrN) layers in CrN/Cr multilayer thin films. The CrN layers of a CrN/Cr multilayer film deposited on a Ti6Al4V substrate by arc ion plating form both a randomly oriented mixed crystal structure and a {112}-oriented structure. Therefore, accurate stress measurement of the CrN layers cannot be performed by applying the sin2ψ x-ray method assuming an isotropic homogeneous material. To overcome this obstacle, the proposed method to measure the residual stress uses four CrN-422 diffractions: at ψ = 0°, 33.56°, 48.19°, and 60.00°. Next, the authors vary the density of Cr droplets on the film surface to evaluate how it affects the residual stress in the CrN/Cr multilayer film. The results indicate that the Cr layer has a residual compressive stress of −350 to −530 MPa and that the two CrN layers have a very large residual compressive stress of −3.5 to −8.2 GPa. In addition, both residual compressive stresses decrease with increasing droplet density