Simulation of the profile of a sample’s X-ray diffraction line in diffusion metal saturation

This article deals with methods of non-destructive control of diffusion-saturated layers of polycrystalline alloys, and in particular, in steel hardening. There exist simple and reliable X-ray techniques of studying diffusion processes. Their main advantages are the safety, availability and absence of necessity to destroy the sample. Diffraction scattering of characteristic X-ray character radiation on a crystal lattice of a polycrystalline alloy contains information on the interior structure and concentration distribution of the diffusing material (carbon used as the diffusant impurity) in the solvent lattice (iron alloy) after isothermal annealing. Application of numerical methods makes it possible to simulate the shape of the line profile by varying the parameter of the alloy lattice, caused, for example, by diffusion penetration of carbon in steel. This approach is used for choosing the best conditions of saturating the surface of a metal alloy for the case of steady- source diffusion. With some assumption, the application of the calculation algorithm shows good approximation for the carbonization of polycrystalline alloys, which makes it possible to determine the degree of the diffusion saturation depending on the process parameters and to control them. The curve variations are related to the gradient of concentration of the diffusant and the depth of X-ray penetration. An algorithm of simulation has been developed and tested allowing prediction of diffusion area parameters in carbonization. It is shown that the depth of investigation using X-rays makes it possible, under certain conditions, to obtain information on the dimensions of the diffusion area in layers considerably in excess of half thickness values. The experimental data obtained in carbonization of a sample are compared with the results of simulation of a diffractive profile.