Abstract:In order to achieve the strength-ductility synergy and improve the work-hardening capacity, Ti64 based composites with dispersive nanoscaled TiB whiskers inside grains were fabricated by plasma rotating electrode process coupled with spark plasma sintering. Based on the rapid eutectic reaction, the nanoscaled TiB whiskers exhibited ultra-fine network distribution in composite powders. During the spark plasma sintering process, the network dissolved, and TiB followed the Ostwald ripening mechanism and merged along the (100) plane. The intragranular TiB whiskers could significantly refine the primary β grain and α lath. The ultimate tensile strength of the composite with only 2 vol.% TiB whiskers was enhanced to (1123±17) MPa while the elongation was similar to that of the as-sintered Ti64 alloy with approximately 8%. The strength-ductility synergy effect was mainly attributed to the significant grain refinement and the work-hardening ability improvement contributed by intragranular nanoscaled TiB.

Key words: titanium matrix composites; nanoscaled TiB whisker; spark plasma sintering; thermodynamic calculation; microstructure; mechanical properties