Microstructure Characteristics and Tribological Performances of LPBF-Processed TiC_p/TA15 Composite.

Area of Science:

• Materials Science
• Tribology
• Additive Manufacturing

Background:

• Microstructure and precipitate features are crucial for titanium matrix composites (TMCs) tribological performance.
• Laser powder bed fusion (LPBF) is an additive manufacturing technique used for fabricating TMCs.

Purpose of the Study:

• To investigate the influence of microstructural evolution on the tribological performance of TiCp/TA15 composites fabricated via LPBF.
• To understand the wear mechanisms of as-built and heat-treated TMCs.

Main Methods:

• Fabrication of TiCp/TA15 composites using LPBF.
• Heat treatment of the as-built composite at 750 °C for 2 h (HT-750) to achieve a uniform duplex (α + β) microstructure with enhanced TiC precipitation.
• Systematic investigation of microstructural evolution and tribological performance, including microhardness, friction coefficient, and wear rate.

Main Results:

• The HT-750 composite showed increased microhardness (459.2 ± 3.1 HV) compared to the as-built composite (360.2 ± 6.4 HV).
• The friction coefficient decreased from 0.649 ± 0.167 (as-built) to 0.581 ± 0.111 (HT-750).
• The wear rate significantly reduced from 8.24 ± 0.44 × 10⁻⁴ mm³/N·m (as-built) to 4.81 ± 0.39 × 10⁻⁴ mm³/N·m (HT-750), indicating enhanced wear resistance.
• The improved performance is attributed to the synergistic effect of the duplex matrix and TiC particles, enhancing load-bearing capacity and suppressing plastic deformation.
• Wear mechanisms differed: as-built composites experienced delamination, oxidative, and abrasive wear due to plastic deformation, while HT-750 composites showed dominant oxidative wear with minor abrasive wear and delamination.

Conclusions:

• Heat treatment at 750 °C significantly enhances the tribological performance of additively manufactured TiCp/TA15 composites.
• The duplex microstructure and TiC precipitation in HT-750 composites improve hardness and wear resistance by mitigating plastic deformation and damage.
• Understanding these microstructural-tribological relationships is key for designing advanced TMCs for demanding applications.