Fig. 1. Microstructure characterization of coarse-grained Ti-10V-2Fe-3Al after heat treatment (referred to as CG). (a) Inverse pole figure map along the Y axis. The Y axis is parallel to the axis of the bar. (b) Selected area electron diffraction pattern along the $ [\bar{1}11] $ β zone axis.

Fig. 2. Metallographic microscopes of the CG samples after different RASP processing, showing a gradient deformation structure from the surface to the interior. (a)-(c) refer to RASP1, RASP3 and RASP5, respectively.

Fig. 3. XRD patterns of the CG samples after different RASP processing.

Fig. 4. Representative EBSD maps obtained from the surface of RASP1. (a) BC map. (b) IPF map of α″ martensite and β phase superimposed with BC map. (c) IPF map of β phase superimposed with BC map. (d) KAM map showing the strain gradient.

Fig. 5. Representative EBSD maps obtained from the center of the RASP1 sample. (a) IPF map of α″ martensite superimposed on the BC map. (b) IPF map of β phase superimposed on the BC map. (c) KAM map. (d) Enlarged view of the region marked with the white rectangle region in (a). (e) Stereographic projections of α1'' and α2'', in the region marked with the blue oval in (d).

Fig. 6. (a) TEM image and (b) SAED pattern of a representative microstructure at the depth of ~50 μm in an ultrafine zone of RASP1.

Fig. 7. TEM characterization of a representative microstructure at the depth of ~300 μm in RASP1, corresponding to a transition zone. (a) Blocks of β phase and α″ martensite. (b) SAED pattern. (c) Dark field image of α″ martensite. (d) Dark field image of β phase.

Fig. 8. TEM characterization of a representative microstructure at a depths of ~300 μm in RASP5, corresponding to a transition zone. (a) Blocks of β phase and α″ martensite. (b) SAED pattern of the white-circle region in (a). (c) SAED pattern of the red-circled region in (a). (d) Dark field image of αT''.

Fig. 9. Microhardness distributions along the depth for the CG and RASPed samples.

Fig. 10. Strengthening of Ti-10V-2Fe-3Al alloy by RASP. (a) Engineering stress-strain curves for the CG and RASPed samples. (b) Work hardening rate as a function of true strain for the CG and RASPed samples. The inset in (b) shows the true stress-strain curves.

Fig. 11. Fractography of Ti-10V-2Fe-3Al alloy after tensile deformation (a) CG. (b) RASP1. (c) RASP3. (d) RASP5. (e, f) High magnification of the center zone of CG and RASP5, respectively.

Fig. 12. Representative EBSD maps obtained from the center of RASP1 after the tensile deformation (a) BC map. (b) IPF map of α″ martensite superimposed on the BC map. (c) KAM map. (d) Enlarged view of the region marked with the white rectangle in (b). (e)-(g) Stereographic projections of αV1'', αV2'' and αV3'', respectively, indicated in (d).

Fig. 13. TEM characterization of a representative microstructure at a depths of 300 μm in RASP1 after tensile deformation. (a) Hierarchical twin structure of α″ martensite. (b) SAED pattern.