Two-level model of the grain boundary diffusion under electron beam action

• Published in: Computational materials science 2021-08, Vol.196, p.110548, Article 110548
• Main Authors: Knyazeva, Anna, Kryukova, Olga, Maslov, Alexey
• Format: Article
• Language: English
• Subjects: Chemical reactions; Diffusion; Grain boundary; Numerical modeling; Transition zone; Two-level model
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2021.110548

[Display omitted] •Diffusion and chemical reaction in grain boundaries and triple junction are studied.•The formation of transient zone between a substrate coating interface is studied.•The dynamics of the phase structure formation for different materials is analyzed.•The model allows evaluating of effective properties in the transition zone. A two-level model of transition zone formation between a polycrystalline substrate and its protective coating under pulsed electron beam exposure with the isolation of individual grain boundaries at the mesolevel has been proposed. Possible chemical reactions and different nature of diffusion in the volume of the grains and along the grain boundaries are taken into account. Physical processes at the mesolevel are reflected in the thermal macro model for the whole sample. Both diffusion coefficients and chemical reaction rates depend on temperature. The different nature of the transition zone formation process between the coating and the substrate is revealed for grains of different sizes. The modification of coatings from tantalum and from silicon on TiNi-surface is studied as examples. The method for effective properties estimation suggested in this work uses the averaging and the integral rule taking into account the form and size of grains and the composition changing during electron beam treatment.