Yurii Ivanov

Surface Doping of Steel with an Intense Pulsed Electron Beam

Surface doping of AISI420 steel is carried out in a single vacuum cycle, and consisted of spraying a thin (0.5 μm) film of Zr-Ti-Cu alloy by electric-arc sputtering of a cathode of the composition Zr-6 at.% Ti-6 at.% Cu, and the subsequent irradiation of the system “film (Zr-Ti-Cu alloy) / (AISI420 steel) substrate” with an intense pulsed electron beam. It is shown that the concentration of zirconium in the surface layer of steel decreases with an increase in the energy density of the electron beam (ES). It is established that formation of a surface alloy is accompanied by the following: formation of a cellular crystallization structure (the average cell size increases from 150 nm at ES = 20 J/cm2 to 370 nm at ES = 40 J/cm2); formation of a dendritic crystallization structure in the presence of refractory element particles (titanium or zirconium); decomposition of a solid solution with the release of zirconium carbide particles (particle sizes increase from (10-15) nm at ES = 20 J/cm2 to (30-40) nm at ES = 40 J/cm2). Particles of the carbide phase based on chromium of the composition Cr3C2, Cr7C3 and (Cr, Fe)23С6, along with zirconium carbide particles, are revealed upon the irradiation of the system “film (Zr-Ti-Cu alloy) / (AISI420 steel) substrate” with an intense pulsed electron beam (ES = 40 J/cm2). Chromium carbide particles have a round shape; their sizes vary from 40 nm to 60 nm. The analysis of phase transformation diagrams taking place under equilibrium conditions in systems Fe-Zr-C; Cr-Zr-C; Fe-Cr-Zr is carried out. It is established that ultra-high cooling rates that occur during the irradiation of the system “film (Zr-Ti-Cu alloy) / (AISI420 steel) substrate” with an intense pulsed electron beam impose restrictions on formation of phases of the intermetallic type. It is suggested that formation of predominantly carbide phases in the surface layer of the material is conditioned upon high mobility of carbon atoms in steel.

Electron-Ion-Plasma Doping of Aluminum Surface with Copper and Titanium - A Comparative Analysis of the Formed Structure and Properties

Deposition of a titanium or a copper film onto the surface of commercially pure A7 aluminum and irradiation of the “film/substrate” system with an intense pulsed electron beam are carried out in a single vacuum cycle. Formation of a surface doped layer with a thickness of (20-30) μm is revealed. It is shown that the modified layer has a multiphase structure of a cellular rapid solidification of the submicron-nanosized range. Irradiation parameters are determined. It is established that the developed modification method allows forming a surface doped layer with the microhardness more than 4 times (Ti-Al alloy) or more than 3 times (Cu-Al alloy) greater than the microhardness of A7 aluminum; the wear resistance of the surface alloy Ti-Al exceeds the wear resistance of the initial aluminum in ≈2.4 times; doping of aluminum with copper is accompanied with an increase in the wear resistance of the material in ≈1.5 times.

Multicycle Surface Alloying of Aluminum with Titanium: Structure and Properties

Commercially pure A7 aluminum was surface alloyed with commercially pure titanium on COMPLEX equipment under unified vacuum conditions through vacuum arc evaporation and deposition of a thin Ti film and intense electron beam irradiation of the film–substrate system using a plasma-cathode pulsed electron source. The number of deposition–irradiation cycles was 20. The Ti film thickness in each cycle was 0.5 μm. After multicycle alloying, a modified surface layer of up to 60 μm thick was formed representing a multiphase structure of rapidly solidified submicro-and nanograins. The microhardness of the Ti–Al surface alloy (irradiation at 15 J/cm2, 50 μs, 10 pulses) was more than 8 times the microhardness of A7 aluminum, and its wear resistance and friction coefficient were respectively 45 times higher and 1.2 times lower than the values in the initial material. The chief cause for the improved mechanical and tribological properties of commercially pure A7 aluminum is the formation of an extended intermetallic layer.

Structure and properties of strengthening layer on Hardox 450 steel

ABSTRACT The microstructure and microhardness distribution in the surface of low-carbon Hardox 450 steel coated with alloyed powder wires of different chemical compositions are studied. It is shown that the microhardness of 6–8u2009mm-thick surfaced layer exceeds that of base metal by more than two times. The increased mechanical properties of surfaced layer are caused by the submicro and nanoscale dispersed martensite, containing the niobium carbides Nb2C, NbC and iron borides Fe2B. In the bulk plates, a dislocation substructure of the net-like type with scalar dislocation density of 1011u2009cm−2 is observed. The layer surfaced with the wire containing B possesses highest hardness. The possible mechanisms and temperature regimes of niobium and boron carbides in surfacing are discussed.