Surface doping of VT6 alloy with zirconium by pulsed electron-beam mixing of predeposited multilayer Zr/Ti film

Abstract

We have studied characteristics of the surface doping of VT6 alloy (Ti-6Al-4V) with zirconium, which was effected in order to reduce the concentrations of Al and V at the surface. The doping was performed by liquid-phase mixing of a [Zr(20 nm)/Ti(20 nm)]12 multilayer film with a total thickness of 480 nm and the substrate (VT6 alloy) under the action of low-energy (∼20 keV) pulsed high-current electron beam (2.5 μs, 3.5 J/cm2). It is established that the pulsed beam-induced melting leads to the homogeneous mixing of all Ti/Zr nanolayers and the diffusion of Zr into substrate to a depth of ∼0.5 μm. As a result, the surface layer with a thickness of ∼0.5 μm is free of Al and V atoms and has a single-phase submicrocrystalline structure of α-Ti70Zr30 solid solution. Subsequent vacuum annealing leads to a decrease in the average grain size in the nearsurface layer to 90 nm and to an increase in the nanohardness of the doped layer.