Investigation of Deformation Mechanisms in β-Type Ti-35Nb-2Ta-3Zr Alloy via FSP Leading to Surface Strengthening
School of Engineering
NSF, National Science Foundation;
NSF, National Science Foundation
Friction-stir processing (FSP) is used to prepare Ti-35Nb-2Ta-3Zr alloys via different processing routes. Dislocation walls and tangles, deformation-induced α″ martensite, and deformation-induced ω phase are observed. The dominant deformation mechanisms are altered from deformation-induced α″ martensitic transformation and dislocation walls to twinning upon increasing the FSP passes. A reverse deformation-induced ω to β transformation and de-twinning process are observed together with grain refinement to the nanoscale. Meanwhile, compressive distortions along ω direction are favorable for the transformation from ω to β.