Improved Strength-Ductility of Ti-6Al-4V Casting Alloys with Trace Addition of TiC-TiB₂ Nanoparticles

In this work, a high strength-ductility Ti64 cast alloy, containing trace TiC-TiB₂ nanoparticles, was fabricated by adding dual-phased nano-TiC-TiB₂/Al master alloys to the molten Ti64 alloys. The trace addition of the TiC-TiB₂ nanoparticles (0.1 wt%) simultaneously reduced the size of the β grains, the α laths, and the α colony size of the lamellar structure during casting and suppressed the coarsening of the α laths during heat treatment. The yield strength and the uniform elongation of TiC-TiB₂/Ti64 were increased by ~130 MPa and 2%, respectively. The simultaneously improved strength and ductility of the TiC-TiB₂/Ti64 were attributed to the decrease in the α colony size of the lamellar structure, the significant refinement of the grains and α laths, and the pinning effect of nanoparticles.