Evaluation of Concentration Dependent Diffusivities of Manganese inthe Diffusion Joint Fe/FeMn-Steel by Means ofMathematical–Analytical Methods

摘要

When developing new types of materials with special properties for the automotiveindustry, steels with high content of manganese (up to 25 wt. % Mn) were studied. These steelsembody increased failure resistance, high level of deformation hardening, plastic response and highvalue of energy absorption in crash situations [1,2]. The aim of our work was to study an interactionof a FeMn alloy with pure iron from the view of diffusion processes. For that purpose, diffusionjoints Fe/FeMn-steel were created and long-term heated at the temperatures of 800, 900 and 1050°C. Dependences of diffusivities of Mn on its concentration were calculated from concentrationprofiles of manganese after diffusion heating applying three analytical methods. In the first method,constant values of diffusivities D1, i = 1,2 for both Fe and steel were taken into account. In thesecond case a modified Matano-Boltzmann method utilizing polynomials was applied, whichsimplifies solution in numerous cases. The third method performs the solution of the non-linearequation of diffusion on the assumption of a linear dependence of diffusivity on concentrationapplying a procedure based on perturbation calculus. The results of the solution will be graphicallydocumented in details together with the description of experiments.