Synergistic enhancement of strength-ductility balance of TZM alloy through c-ZrO2 combined with large deformation and annealing

In this work, new TZM alloys containing 0.5wt% and 1.0wt% ZrO2 were prepared by powder metallurgy method, and their annealed microstructures and mechanical properties were studied. The TZM alloy sheet with 94% deformation was recrystallized at 1200°C, and the elongation was greatly increased, and its UTS, YS and EL were 573 ± 10MPa, 431 ± 7MPa and 44 ± 0.2%, respectively. After adding 0.5wt% c-ZrO2, the best strength-ductility balance was achieved, and its UTS, YS, EL and PSE are 621 ± 3MPa, 527 ± 4MPa, 41.3 ± 0.58% and 25.6GPa·%, respectively, which was much larger than the PSE combinations of most Mo and TZM alloys. Microstructure analysis shows that the excellent synergistic effect arises from the low O impurity content and the control of dislocation density and dislocation slip by c-ZrO2 and the annealing process. Within the alloy, Ti and Zr react with O to produce TiO2 and ZrTiO4, which reduces the content of O impurities. Annealing provides sufficient space for dislocation slip, which coordinates the rotation of grain orientation during the stretching process. Coupled with the low O impurity concentration, results in excellent ductility of TZM alloys. Additionally, c-ZrO2 can effectively fix dislocations within the grains and interact strongly with dislocations, consequently enhancing the strength of the TZM alloy.