Fig. 1. Fabrication of Ti-TiB2 cored wire: a) the photographs of starting materials; b) the schematic diagram of fabrication procedure.

Fig. 2. Experimental arrangement for wire-feed arc deposition.

Fig. 3. Microstructures of a solidified wire end: a) cross-sectioned morphology; b) magnified image for zone 1; c) magnified image for zone 2, wherein c2) is the element distribution along the white arrow in c1), c4) is the XRD spectrum acquired from zone 2; d) magnified image for zone 3.

Fig. 4. Gibbs free energy curves of the possible chemical reactions between V and TiB2.

Fig. 5. Transfer behavior of droplets under different welding currents in one transfer cycle: a) 110 A; b) 120 A; c) 130 A; d) 140 A.

Fig. 6. Oscillograms of welding electric signals under various welding currents: a) 110 A; b) 120 A; c) 130 A; d) 140 A.

Fig. 7. Variation of droplet detachment time and transfer frequency with a) and b) welding current; c) and d) wire feeding speed.

Fig. 8. Surface appearance, cross-sectioned and longitudinal-sectioned morphology of as-deposited TiB/Ti composite coatings.

Fig. 9. XRD spectra of TiB/Ti composite coatings produced by different processing parameters.

Fig. 10. Microstructure characteristic of TiB/Ti composite coating: a) SE mode; b) BSE mode; TEM BF images of c) TiB and d) α/β lamella; e) and f) SAED patterns of α/β lamella at different zone axes; g) pole figure of β-Ti at [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]] projection direction; h) pole figure of α-Ti at [[11], [12], [13], [14], [15], [16], [17], [18], [19], [20]] projection direction; i) OM and j) SEM image of interfacial region.

Fig. 11. Microstructure analysis on a TiB2 particle inclusion: a) and b) BSE image; c) element map of zone 1; d) EBSD results of zone 2.

Fig. 12. Content and distribution of TiB whiskers in TiB/Ti composite coatings produced by different welding currents (BSE mode): a1)-d1) top region; a2)-d2) middle region; a3)-d3) bottom region; e) the area fraction of TiB in different regions.

Fig. 13. Morphology of α/β lamellae in the coating prepared by a) 110 A; b) 120 A; c) 130 A; d) 140 A, e) shows the α/β lamellae of Ti6Al4V substrate.

Fig. 14. Content and distribution of TiB whiskers in TiB/Ti composite coatings produced by different wire feeding speeds (SE mode): a1)-c1) top region; a2)-c2) middle region; a3)-c3) bottom region; d) the area fraction of TiB in different regions.

Fig. 15. The Vickers micro-hardness of TiB/Ti composite coatings: a) and b) hardness profile; c) and d) average hardness.

Fig. 16. The microstructure of the deformation zone beneath a Rockwell indentation.