Computer Simulation of Diffraction Technique Applied for Measurements of Surface Stress Gradients

Modern surface treatment technologies, like laser treatment or surface modifications by ion beams, introduce high residual stresses characterized by strong gradients of stress distribution in the depth of treated surface. The diffraction methods of stress gradient determination based on analysis of nonlinearity of d, - sin2 dependency is not sufficient to practical using because experimental criterions predicting the existence and level of stress gradient are absent. Experimental attempts to develop the methodology of stress gradient determination are not successful because of the difficulty to prepare the samples with known parameters of stress gradient. Computer simulation of diffraction profile formed by reflection from surface layers with stress gradient allows to simulate experimental dependency d, = f(sin2) permitting to obtain the relationships between the stress gradient parameters, non-linearity of d, = f(sin2) and broadening of diffraction line caused by stress.