Study of niobium base alloys surface after plastic deformation, nitriding and double annealing

The method of X ray photoelectron spectroscopy was applied to investigate the surface of niobium base alloy 5VMTs subjected to 70 % reduction, nitriding at 800 deg C, vacuum annealing at 1000 deg C for 1.5 h and vacuum annealing at 1250 deg C for 4 h. It is shown that in the process of mechanical and chemical heat treatment the redistribution of elements on the surface takes place. At final stages a decrease of nitrogen content is observed. A conclusion is made that the combined treatment of the alloy results in the formation of clathrates responsible for its high service properties