Surface alloying of stainless steel 316 with copper using pulsed electron-beam melting of film–substrate system V.P. Rotshtein a, ⁎ , Yu.F. Ivanov b , A.B. Markov b , D.I. Proskurovsky b , K.V. Karlik b , K.V. Oskomov b , B.V. Uglov c , A.K. Kuleshov c , M.V. Novitskaya c , S.N. Dub d , Y. Pauleau e , I.A. Shulepov f a Tomsk State Pedagogical University, 75 Komsomolsky Ave., Tomsk, 634041, Russia b Institute of High-Current Electronics, 2/3, Akademicheskii Pr., Tomsk, 634055, Russia c Belarussian State University, 4 F. Scorina Ave., Minsk, 220080, Belarus d Institute for Superhard Materials, 2 Avtozavodskaya St., Kiev, 07070, Ukraine e National Polytechnic Institute of Grenoble, CNRS-LEMD, 25 Rue des Martyrs, B.P. 166, 38042 Grenoble cedex 9, France f Nuclear Physics Institute at Tomsk Polytechnic University, 2a Lenin Ave., Tomsk, 634050, Russia Available online 27 December 2006 Abstract The surface morphology, chemical composition, microstructure, nanohardness, and tribological properties of a film (Cu)–substrate (stainless steel 316) system subjected to pulsed melting with a low-energy (20–30 keV), high-current electron beam (2–3 μs, 2.8–8.4 J/cm 2 ) have been investigated. The film was deposited by sputtering a Cu target in the Ar plasma of a microwave discharge. To prevent the local delamination of the film due to the cratering, the substrates were repeatedly pre-irradiated with 8–10 J/cm 2 . Single pulsed melting of this system resulted in the formation of a diffusion layer of thickness 120–170 nm near the interface, irrespective of the energy density. The layer has the subgrain structure consisting of the γ-Fe-solid solution and submicrometer or nanocrystalline Cu particles. The nanohardness and the wear resistance of the surface layer of thickness 0.5–1 μm, including the molten film and the diffusion layer, non-monotonically vary with energy density, reaching a maximum in the range of 4.3–6.3 J/cm 2 . As the pulse number is increased to five in the same range of energy density, the film dissolves in the substrate, and a ∼2-μm-thick surface layer is formed which contains ∼20 at.% Cu. Under these conditions, the segregation of Cu during resolidification leads to the formation of two-phase nanocrystalline layers separating γ-phase grains. © 2005 Elsevier B.V. All rights reserved. Keywords: Pulsed electron-beam melting; Surface alloying; Film–substrate system 1. Introduction Pulsed liquid-phase mixing of film–substrate systems with intense pulsed (10 - 8 –10 - 6 s) electron beams is an efficient method of surface modification of materials. In experiments on binary systems with components of various solubility, it has been established that this method permits to form, due to fast quench- ing from the melt, metastable supersaturated solid solutions and amorphous and nanocrystalline structures, and to synthesize metal silicides and silicon carbide [1–4]. However, this method is still used in fact only in experiments, which is largely related to the lack of information on the effect of surface alloying on the microstructure and properties of structural alloys. The new tech- nology-oriented sources of microsecond low-energy (20–30 keV), high-current electron beams (LEHCEB's) developed in recent years [5,6] give impetus to research in this area. The goal of this work was to study comprehensively the evolution of the surface topography, chemical composition, microstructure, nanohardness, and tribological properties of a Cu/stainless steel 316 system (Cu/SS 316) subjected to the pulsed electron-beam melting. From the viewpoint of surface alloying, this system is of interest since under equilibrium conditions, Cu is immiscible with Fe and Cr (main components of the substrate) in the liquid state and practically does not mix with them in the solid state. This system is of interest also because thin Cu coatings are used for wear protection of steels. Besides, alloying (to 3–5 wt.% Cu) of austenitic SS enhances Surface & Coatings Technology 200 (2006) 6378 – 6383 www.elsevier.com/locate/surfcoat ⁎ Corresponding author. Tel.: +7 3822 49 16 95; fax: +7 3822 49 24 10. E-mail address: rvp@lve.hcei.tsc.ru (V.P. Rotshtein). 0257-8972/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2005.11.007