X-ray radiography of phase equilibria in the V-N system

The study was concerned with fragments and finely ground material samples. X-ray techniques were used to investigate the phase composition of alloys of the system V-N (2.5-13.6 at.% N) slowly cooled to 700-1000 deg C and hardened at 800-1600 deg C. The following phase composition was shown to be equilibrium in the given concentration interval: α-solid nitrogen solution in vanadium or α-phase and hexagonal vanadium β-nitride. Beginning from a concentration exceeding approximately 5 at.% N, martensite transformations were found to take place in α-solid solutions at high-temperature ((>=)1100 deg C) hardening. The investigation results together with data from other studies of vanadium nitrides were summarized in the from of a diagram showing the state of the system V-N (0-50 at.% N) in a temperature range of up to approximately 1600 deg C