Effect of oxygen and nitrogen on microstructure and mechanical properties of vanadium

The effect of oxygen and nitrogen content on the microstructure and mechanical behavior of vanadium was investigated. Vanadium specimens containing 40–4536 ppm nitrogen and 624–9092 ppm oxygen, respectively were prepared using diffusion heat treatments. The specimens were characterized with respect to chemical composition, microstructure and mechanical properties. Both V-O specimens and V-N specimens had single phase microstructure with no precipitates. Increase in oxygen and nitrogen content increased hardness and tensile strength and decreased ductility. The specimens were characterized for grain boundary segregation using scanning transmission electron microscopy (STEM) equipped with super-X EDS and high resolution ion microprobe (NanoSIMS). The mechanical properties were discussed in view of the measurements of composition and microstructure.