Anzor Guldamashvili

Abstract:

The hardening of nano-sized Mo layers of (110) and (111) orientation after Ar ion implantation was studied. Ion bombardment was carried out successfully for materials modification and simulation of reactor irradiation. Monocrystalline Mo samples of 99.99 at. % purity obtained by zone melting were used as initial material. Polished plane-parallel specimens of 1.5 mm thickness and 15 mm in diameter with roughness of 7.5 nm were prepared for ion implantation. The conditions of Mo implantation with Ar ions were: energy-60 keV; fluences Φ=1•1014, 1•1015, 1•1016 ion/cm2; temperature T=300-350 K. The microhardness was studied by the Vickers method on Shimadzu dynamic ultra-micro hardness tester DUH-211S. Testing was performed at load-unload mode with constant speed of deformation in the range of loads 3-1500 mN. Initial microhardness of Mo <110> and <111> were 1.85 GPa and 1.95 GPa respectively. The experimental results of relative hardening H/H0 of Mo samples irradiated with various fluences and radiation damage doze-D, dpa will be presented and dicussed. Research results show considerable hardening of initial material. Radiation hardening of Mo is caused by creation of the new centers of dislocation pinning, which increases the resistance to the motion in the plane of dislocations slip. After isothermal treatment of the samples the microhardness returns to initial value. Temperature range of annealing coincides with 'annealing' of the increment of bcc metals hardness in reactor and almost output of all argon atoms from the crystal.