Deformation-induced microstructure refinement in primary α phase-containing Ti–10V–2Fe–3Al alloy

Microstructural evolution in primary α phase-containing Ti–10V–2Fe–3Al alloy subjected to cold forging under different applied strains was studied. Experimental results showed that, even at a strain of 0.1, stress-induced α″ martensites were abundantly produced within the β matrix, resulting in alternative α″/β lamellae. Shear bands initiated and grew across α″/β lamellae as the strain increased to 0.35. When the strain increased to 1.2, the volume fraction of shear bands significantly increased and the grains were almost occupied by the shear bands. Interestingly, nanocrystallines were observed inside shear bands. While in the primary α phase, slip was always the predominant plastic deformation mode and dislocations were accumulated to a high density within the strain range from 0.1 to 0.35. When the strain was up to 1.2, the dislocation density was further increased and α/β interface boundary became ill-defined. However, no grain refinement was observed in the α phase. The microstructure refinement in the β matrix could be attributed to that stress-induced α″ martensitic transformation promoted the initiation, thickening and coalescence of shear bands. The plastic deformation combined with martensitic phase transformation could provide a potential effective technique to produce nanocrystalline materials.

Research highlights▶ Nanocrystallines are produced in Ti–10V–2Fe–3Al alloy subjected to cold forging. ▶ The stronger refinement capability of β phase than α phase in Ti–10V–2Fe–3Al alloy. ▶ The martensitic transformation accelerates microstructure refinement.