g of a niobium vanadium alloy powder prepared according to example 1 and having the following purity and physical properties specific surface area according to bet 4 34 m 2 g apparent density according to scott 14 3 g inch flowability according to hall flow 22 s particle size determination according to mastersizer d10 65 1 d50 170 7 d90 292 7 u03bcm were intimately mixed with 566 5 g of niobium pentoxide nb 2 o 5 lt 45 u03bcm having the following contents u03c3 al as ca co cr cu fe ga k mg mn mo na ni pb sb si sn ta ti w v zr lt 25 ppm and placed into a molybdenum boat the latter was then heated for 6 hours at 1250 u00b0 c under weakly flowing hydrogen the resulting product sample a had the composition nbo and had the following contents and physical properties specific surface area according to bet 2 31 m 2 g apparent density according to scott 13 9 g inch 3 flowability according to hall flow 29 s particle size determination according to mastersizer d10 22 3 d50 123 4 d90 212 7 u03bcm in an analogous manner there was prepared as comparison sample from a niobium powder prepared by published proposals of the applicants according to de 19831280 a1 and having the following contents and physical properties specific surface area according to bet 4 01 m 2 g apparent density according to scott 13 6 g inch 3 flowability according to hall flow 30 s particle size determination according to mastersizer d10 44 7 d50 156 2 d90 283 9 u03bcm and a niobium pentoxide nb 2 o 5 lt 45 u03bcm having the following contents u03c3 al as ca co cr cu fe ga.