Formation of introduction solid solutions and phases under the conditions of ion bombardment of metals in the glow discharge

Abstract

Regularities of interaction of iron, steels, nickel, copper, titanium with light elements and inert gases in the plasma of the glow discharge studied by methods based on the use of radioactive indicators 55Fe, 44Ti, 14C, 13N, 85Kr, 41Ar (layer-by-layer radiometric analysis of residual integrated activity, macro- and microautoradiography, activation autoradiography), as well as metallography, X-ray analysis and spectral analysis. Processing was carried out according to the diode circuit with parameters of 1 - 55 hours, 0.2 - 2 kV, ~ 500 K. Neutral (argon, krypton) and saturating (nitrogen, ammonia, methane) media were used for processing in the discharge, and further processing of metals previously saturated with nitrogen or carbon was carried out in a neutral medium. It is established that in the process of introduction into metals (Fe, Ti) under the action of a glow discharge burning in a saturating medium, atoms soluble under equilibrium conditions of elements (N, C), there are interstitial solutions and phases that differ from those formed in isothermal annealing, only the presence of supersaturated solid solutions and some violation of the stoichiometry of carbides and nitrides, as well as a steeper decrease in the concentration of the alloying impurity with increasing distance from the surface. The shape of the concentration profiles outside the layer of the interstitial phase is described by an exponential dependence on the square of the penetration depth. As for the penetration into copper of nitrogen, carbon, argon or krypton atoms, insoluble under equilibrium conditions, in ion bombardment in appropriate media from the treated surface to the end of the diffusion zone there is only a solid solution with a concentration that decreases by the exponent. It turned out that further treatment of nickel, iron and steel saturated with light elements by argon and krypton ion bombardment leads to redistribution of alloying impurities, separation of interstitial phases mainly at grain boundaries, surface or at some distance from the surface, which contributes to some disturbance of concentration profile. When processing pre-saturated copper interstitial phases do not occur, but the type of profile changes dramatically, but from the maximum to the end of the diffusion zone is described by the exponent. It is shown that the use of saturating and neutral media, as well as their sequential application for processing in the glow discharge makes it possible to create predetermined doping profiles and enter the required amount of doping impurity. Keywords: glow discharge, radioactive isotopes, light elements, inert gases, diffusion, formation of phases and solid solutions.