Microstructure control to improve mechanical properties of vanadium alloys for fusion applications

Powder metallurgy (P/M) methods including mechanical alloying (MA) treatment may be useful to improve both radiation resistance and high-temperature strength that are major concerns in the use of V–4Cr–4Ti for fusion reactor structural applications. For the P/M methods, however, there is a critical issue that solute oxygen and nitrogen contained in the starting powders and introduced through the fabrication processes cause a serious loss of ductility. In this paper, a process for microstructure control to solve the issue is proposed and applied to fabricate a vanadium alloy. The microstructures and mechanical properties of the fabricated alloy are also presented. It is shown that the proposed process is very effective in removing solute oxygen and nitrogen from the matrix resulting in a significant suppression of the ductility loss and that optimizing MA conditions will bring about further improvement in the ductility at low temperatures.