COMPARATIVE-STUDY OF THE RECRYSTALLIZATION OF PURE NIOBIUM AND A NB-1 WT-PERCENT ZR ALLOY

A comparative study on work hardening, recovery, recrystallization and grain growth of pure niobium and a Nb-1 wt.% Zr alloy has been carried out. Both materials were produced by electron beam melting. The deformation process (swaging) was the same for both materials. The degrees of deformation, which varied in the range 63 to 99 %, were calculated by the reduction in cross-sectional area. The annealing was performed in the following range of temperatures: 700 to 1300 degrees C for pure niobium and 800 to 1300 degrees C for the alloy. All the zirconium in the alloy was in solid solution, and the main effects of the zirconium addition were: solid solution hardening, increase of about 100 K in the temperatures of both start and end of recrystallization and strong inhibition of grain growth. Considerable softening was shown by both materials due to recovery processes.