Fig. 1 a Schematic of the preparation processing route and the corresponding microstructure of the TiB/Ti-6.5Al-2Zr-1Mo-1V-0.3Si composite, b XRD pattern of the as-forged composite

Fig. 2 Schematic of fatigue specimen and load curve: a orientation of specimens in forge piece, b fatigue test specimen, c fatigue load curve with R ratio of 0.1

Fig. 3 BSE images and phase volume fraction of the as-forged TiB/Ti-6.5Al-2Zr-1Mo--1V-0.3Si composite: a microstructure captured from Y-Z plane, b volume fraction of α-Ti, β-Ti and TiB corresponding to the microstructure in a, c the silicide precipitated along the α/β interface, d a small amount of transformed β was retained in the matrix

Fig. 4 TEM characterizations of the as-forged TiB/Ti–6.5Al–2Zr–1Mo–1 V–0.3Si composite: a bright-field image showing (TiZr)5Si3 and β phase, b HRTEM image corresponding to a rectangular region in a, c SAED pattern of the rectangular region in a, ${\text{[000}\stackrel{\mathrm{-}}{1}\text{]}}_{{{\text{(TiZr})}_{5}\text{(Si})}_{3}}$//[$\stackrel{\mathrm{-}}{1}$ 11]β

Fig. 5 Mechanical properties of the as-forged TiB/Ti-6.5Al-2Zr-1Mo-1 V-0.3Si composite: a stress-strain curve, b S-N curve

Fig. 6 Typical fracture morphologies of the specimen at different stress levels: a 900 MPa, b 800 MPa, c 700 MPa, d 650 MPa, e 600 MPa, f high-magnification images of the rectangular regions in e. The bottom left of images shows the high-magnification morphology of the rectangular regions

Fig. 7 Fatigue fracture surfaces of the as-forged TiB/Ti-6.5Al-2Zr-1Mo-1 V-0.3Si composite with Nf = 5,236,326 cycles at maximum stress of 600 MPa: a TiB in crack-initiation facet corresponding to the rectangular regions in Fig. 6f; b TiB in crack-propagation facet; c fatigue striation through the TiB; d fatigue striation morphology through the silicides; e and f EDS mapping of Zr and Si elements corresponding to d

Fig. 8 Crystallographic orientation of crack-initiation grain and neighboring grains in the shortest lifetime specimen: a an overview of the crack-initiation region located in the convergence of radial ridges, b an illustration of cross section plane sectioning along the yellow dashed line in b, c the superimposed image of fractography and IPF map, d the IPF of F1 and F2 grains superimposed basal Schmid factor along the loading direction, e the IPF of F1 and F2 grains corresponding to the facet normal, f the IPF of crack-initiation grain and neighboring grains along the loading axis

Fig. 9 Crystallography of the crack-initiation site and neighboring grains in the longest lifetime specimen: a schematic of the sectioning plane across the crack-initiation facet and propagation region, b the composite micrographs showing the IPF map of the facet and neighboring grains, c the IPF of F3 grain showing crystallographic orientation of facet relative to the loading axis and the basal Schmid factor, d the IPF of F3 grain corresponding to the facet normal

Fig. 10 SEM and EBSD analysis of the F4 grain at the crack propagating region: a the composite images of the IPF map and the fracture surface, b the facet surface of F4 grain, c the IPF of F4 grain superimposed basal slip Schmid factor along the loading direction, d the IPF of F4 grain along the facet normal, e GND density of basal <a> slip, f GND density of prismatic <a> slip

Fig. 11 IPF of the crack-initiation site and neighboring grains of the longest lifetime specimen with Nf = 5,236,326 cycles at maximum stress of 600 MPa

Fig. 12 Identification of fatigue crack initiation after 20,000 cycles: a an overview SEM image of fatigue crack path, b IPF map corresponding to a, c high-magnification image of the region I in a, d high-magnification image of the region II in a, e high-magnification image of the region III in a

Fig. 13 IPF map of the cracked grains and the crack path indicated by black lines and the slip traces of the different slips

Fig. 14 Orientation identification of fatigue initiation cracks and the fractured TiBw: a-e showing the fatigue cracks adjoining the TiBw, f pole figure of fractured TiBw