On influence of irradiation by carbon ions on tantalum structure

Data of experimental studies on tantalum surface structure change and it microhardness in the result of carbon ion implantation are presented. The tantalum samples with purity 99.96 % having cylindrical shape (height 55 mm and diameter 4.5-5 mm) after polish were irradiated by carbon ions with energy 60 keV in the range 5·1016-5·1018 cm-2 at the DIANA facility. The microhardness measurement has been conducted on the PMT-3 device on the irradiated surface and along samples cross section. The microstructure has been examined on the NEOFOT-21 optical microscope, and phase-structural transformations were studied on the 3.0 DRON X-ray diffractometer with application of CuKα radiation. It is determined, that under carbon ion implantation into tantalum surface layers the texture tantalum carbide phases and tantalum monocarbide arise. Post-radiation thermal annealing leads to tantalum monocarbide decay and tantalum carbide particle sizes increase. It is determined, that phases got under C+ implantation have introduction phase structure with dense atom packing. Ion doping leads to tantalum surface hardening. Hardening rate depends on the irradiation fluence. Maximal hardening has been observed on the surface, the maximal microhardness increase extension along whole samples thickness. Due to carbon ions implantation the microhardness is increasing in 3 times near surface, and up to 1.5-3 times over samples thickness