Original Article

The synergistic strength-toughness optimization effect of TiB₂ and TiC composite reinforcing phases in Ti-6Al-4V alloy cladding layers

¹ College of Mechanical Engineering, Jiangsu University of Technology, Changzhou, Jiangsu 213001, PR China
² Army Academy of Armored Forces, Beijing, 100072, PR China

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Received: 13 August 2025
Accepted: 23 December 2025

Abstract

In addressing the challenge of simultaneously improving the hardness, wear resistance, and crack resistance of Ti-6Al-4V alloy cladding layers, laser cladding carried out using three powder ratios: 15% TiC + 85% TC4, 15% TiC + 5% TiB₂ + 80% TC4, and 20% TiC + 80% TC4. A comparative investigation was conducted on the microstructure, phase precipitation, electrochemical corrosion behavior, and basic mechanical properties of the resulting cladding layers. The experimental results showed that in cladding layers reinforced with TiC, an increase in TiC content led to the formation of TiC, α-Ti, and β-Ti. The addition of TiB₂ significantly refined the grain size of the TiC reinforcement, and a low two-dimensional lattice mismatch of 0.98% was observed between TiB₂ and TiC, indicating a strong synergistic effect between the two phases. The hardness of the TiB₂-TiC composite cladding layer reached 628 HV₀.₂, which was 93.23% compared with the substrate and significant higher than the other two cladding ratios. The average friction coefficient of the TiB₂-TiC cladding layer was 0.2660, a 31.90% reduction compared to the 15% TiC cladding layer. Compared with the other two cladding layers, the maximum wear depth decreased by 26.70%, and the wear volume was reduced by 26.17%. Furthermore, the fusion line of the TiC-TiB₂ cladding layer moved downward by 0.319 mm, indicating more uniform thermal diffusion and improved stress transfer characteristics. The self-corrosion potential was –0.1890 V, demonstrating superior corrosion resistance relative to the other cladding ratios. This study reveals the synergistic effect of TiC and TiB₂ composite reinforcing phases in Ti-6Al-4V alloy laser cladding layers, achieving a simultaneous improvement in hardness, toughness, and wear resistance, and providing theoretical and methodological guidance for optimizing the surface properties of such alloys.