Synergistically strengthened TA15 titanium alloy by laser powder bed fusion: Microstructure and mechanical properties

In order to meet the high performance demands of Ti alloy in the aerospace industry, a novel Ti matrix composites reinforced with silicon carbide particles (SiCp) and carbon nanotubes (CNTs) in TA15 Ti alloy was proposed in this work. SiCp+CNTs/TA15 Ti matrix composites samples were successfully fabricated by laser powder bed fusion (L-PBF), and their microstructures and properties were investigated. The SiCp+CNTs/TA15 powder was meticulously prepared through ultrasonic homogenization and vacuum high-speed rotation homogenization, ensuring an even distribution of reinforcements on the powder surface. The optimized processing parameter window for L-PBFed TA15 was determined through Taguchi experiments, ranging from 100 to 125 J/mm³. Further process optimization resulted in the determination of specific optimal printing parameters: a laser power of 210 W and a scanning speed of 900 mm/s. The microstructure evolution of TA15 and SiCp+CNTs/TA15 was revealed through characterization methods such as X-ray diffraction and electron backscattered diffraction, and the influence of microstructure on mechanical properties was further explained. According to the results of microstructure characterization, the strengthening mechanism of SiCp+CNTs/TA15 was analyzed. The strength of SiCp+CNTs/TA15 is significantly improved by the fine grain strengthening and dispersion strengthening of SiCp. Additionally, the elongation of SiCp+CNTs/TA15 is well-preserved due to the crack inhibition properties of CNTs. Finally, a novel Ti matrix composites with excellent comprehensive mechanical properties was obtained, the tensile strength of Ti matrix composites reached 1653 MPa, representing a 32.5% increase compared to the base material, while the elongation remained relatively unchanged. This reinforced SiCp+CNTs/TA15 composite provide a new idea for the additive manufacturing of high-performance Ti matrix composites.