| 研究実績の概要 |
In this study, the respective strengthening contribution of various deformation modes including {332}<113> deformation twinning, dislocation gliding and deformation-induced omega phase transformation during tensile deformation was investigated in the developed alloy, Ti-9Cr-0.2O. The results assist to elucidate how the omega phase transformation works in Ti-9Cr-0.2O during tensile deformation and facilitate to interpret the excellent mechanical property obtained in this alloy. Normal tensile test and interrupted tensile tests stopped at 4.7%, 7%, 12% and 19% strains were performed in the prepared Ti-9Cr-0.2O alloy and the microstructure was examined. The results show that both the strengthening contributions of deformation twins and dislocations gradually increase with the increasing strain during tensile deformation. The dislocations show a much more predominant strengthening effect than the deformation twins during the plastic deformation stage. The omega phases including athermal and deformation-induced omega phases play a strong strengthening effect in the elastic deformation stage. This strengthening effect induced by omega phases increases when strained to 7%, i.e. an early plastic deformation stage, and subsequently decreases gradually with further increasing the strain to 12%, 19% and finally to fracture. This result is considered to be associated with the coarsening of omega particles, the re-orientation of one omega variant to another and the possible reversal transformation of omega phase to beta phase during tensile deformation in Ti-9Cr-0.2O alloy.
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