Two-scale TiB/Ti64 composite coating fabricated by two-step process

Highlights: • A novel integrative TiBw/Ti64 composite structure was synthesized by two-step method. • Two-scale TiB, self-joining structures and strong interface enhance abrasion performance. • Hardness increased with increasing TiB content and decreased with increasing heat input. • Optimized hardness and friction coefficient of composite layer were HRC 60 and 0.14. In order to improve the hardness and wear resistance of Ti materials, TiB/Ti64 composite coatings were synthesized by two-step method. Microstructure analysis reveals that a dense composite layer reinforced by two-scale TiB and well bonded with substrate was synthesized, and the coarse primary TiB prism (width: 7–17.5 μm) and fine eutectic TiB whisker (width: 0.3–1.2 μm) were free of reinforcement/matrix interfacial chemical reaction. Consequently, the hardness of the composite coating was significantly improved by two-scale TiB reinforcements, self-joining structures and strong reinforcement/matrix interface. Nanoindentation tests indicate that coarse primary TiB zone exhibited superior hardness, modulus and wear resistance, which was more beneficial to enhancing the coating performance. Besides, the hardness increased with the increasing TiB content and decreased with the increasing heat input, and the maximum hardness (HRC 60) was obtained by employing 29.4 wt.%TiB₂+Ti64 powders and cladding at 162.7 J mm⁻¹, which is 80.2% higher than that of substrate (HRC 33.3). Meanwhile, the friction coefficient of the composite coating (0.14) was also significantly decreased compared with that of substrate (0.40).