Effect of B4C size on the fabrication and compression properties of in situ TiB2–Ti2AlC/TiAl composites

With the addition of coarse B4C particles (40 μm and 20 μm), combustion synthesis reactions in Ti–Al–B4C systems are incomplete. Some large B4C particles exist in the composites, leading to lowering of the compression strength and ductility. When the size of the B4C particles is reduced to 3.5 μm, pure TiB2–Ti2AlC/TiAl composite has been successfully fabricated for the first time. The in situ synthesized fine TiB2 and Ti2AlC particles (500–700 nm) could enhance the compression strength of the TiAl alloy without sacrificing ductility. The average yield strength, ultimate compression strength, and fracture strain of the pure TiB2–Ti2AlC/TiAl composite fabricated with the addition of 3.5 μm B4C particles are, respectively, 259 MPa, 174 MPa and 0.3% higher than those of pure TiAl alloy.

► The in situ TiB2–Ti2AlC/TiAl composite was fabricated for the first time.
► The compression properties of the composites increase with the B4C size decreasing.
► The synthesized particles enhance the TiAl strength without sacrificing ductility.