Recent progress on room temperature fracture toughness of Nb-Ti-Cr-Si based ultrahigh temperature alloy

Nb-Ti-Cr-Si based ultrahigh temperature alloy possesses good high temperature strength and high temperature oxidation resistance, but its room temperature fracture toughness is poor. In order to improve room temperature fracture toughness, the reason of poor room temperature fracture toughness are discussed, and the effects of integrally directional solidification with the use of a crucible, directional solidification after homogenization treatment and hot press technologies on the room temperature fracture toughness of Nb-Ti-Cr-Si based ultrahigh temperature alloy are reviewed. Finally, the future direction to regarding room temperature fracture toughness of these alloy are proposed.