Microstructural control to improve the resistance to radiation embrittlement in vanadium

In order to improve the resistance to serious radiation embrittlement in refractory metals, a process for microstructural control is presented, with significance of controlling the substance, size, number density and distribution of dispersed particles. The process is applied to vanadium, a metal of group VA, with ultra-fine grains and finely dispersed, thermally stable particles. It is shown that the developed V–(1.6–2.6)%Y alloys have grain sizes between 170 and 340 nm and particle (Y2O3 and YN) sizes between 13 and 25 nm and exhibit the following noted features: (1) The microstructure is stable against vacuum heating at 1573 K for 1 h. (2) The vanadium matrix is very low in solute oxygen and nitrogen, which are responsible for environmental embrittlement of vanadium. (3) The alloys exhibit good tensile strength and elongation at low temperatures; approximately 1.5 times more strength and about 70% of the elongation compared with a V–4Cr–4Ti (Nifs-Heat-1) alloy. (4) The developed alloys show good resistance to neutron irradiation at 563 K to 0.25 dpa and 873 K to 0.60 dpa. These fabrication processes and noted features are applicable to other group VA metals such as tantalum.