Title: Nanostructured gradient coating based on carbide of tungsten in carbon steel

Authors: S.V. Davydov; А.О. Gorlenko

Addresses: Department of Tribotechnical Materials Science and Materials Technology, Bryansk State Technical University, 50 let Oktyabrya bul, 7, Bryansk, 241035, Russia ' Department of Automobile Transport, Bryansk State Technical University, 50 let Oktyabrya bul, 7, Bryansk, 241035, Russia

Abstract: Structural and phase transformations in tungsten-containing functional coatings of carbon steels, obtained in high-energy processes of implanting tungsten carbide micropowders by complex pulse electromechanical processing method, are studied. It is shown that during thermosilic action in the deformation zone, an intensive austenisation of steel occurs with the dissolution of tungsten carbide with the subsequent formation of composite gradient structures as a result of the decomposition of supercooled austenite supersaturated with tungsten both by the diffusion mechanism and by the spinodal decay mechanism. In the case of spinodal decay, in the general case, the diffusion flux is determined not by the concentration gradient, but by the gradient of the chemical potential. In this case, the diffusion processes lead to a state characterised by the condition that the chemical potential μ is constant in a given volume and the system bundles into concentration zones where the condensed phases crystallise. It is shown that individual zones of the tungsten-containing phases of the alloy are in the liquid-phase state and also undergo spinodal decomposition with the formation of highly disperse carbide phases of globular morphology.

Keywords: tungsten-containing coatings; pulsed electromechanical processing; implantation; spinodal delamination of solutions; composite hardening; highly dispersed carbide phases; morphology of tungsten carbide inclusions.

DOI: 10.1504/IJNT.2019.102392

International Journal of Nanotechnology, 2019 Vol.16 No.1/2/3, pp.60 - 68

Published online: 12 Sep 2019 *

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