Precipitation behavior in V-6W-4Ti, V-4Ti and V-4Cr-4Ti alloys

The cold rolled V-6W-4Ti, V-4Ti and V-4Cr-4Ti alloys were annealed at 900 and 1100 deg. C for recrystallization and solid solution, respectively. Large precipitates were found in the 900 deg. C annealed ones with main difference in the number density among the alloys. Followed the heat treatments, the alloys were annealed again at 400-900 deg. C for 1 h or aged at 600-800 deg. C for durations up to 50 h. Precipitation hardening was found in solid solution treated alloys after the annealing below 900 deg. C and after the aging at 600 deg. C. The precipitates are Ti and C-rich ones, without the enrichment of W in the V-6W-4Ti alloy. Results showed that the growth of the precipitates was controlled by the diffusion of interstitial solutes of C, N and O. V-4Cr-4Ti showed much stronger precipitation hardening than the others due to Cr addition