Role of V in microstructure and strength enhancement of 4 vol% nano-TiB2/TiAl composites

Abstract

TiAl alloys exhibit significant properties, such as low density and high specific strength, and can successfully meet the requirements of weight reduction in aviation applications. However, insufficient strength, especially at high temperatures, has always been challenging. To overcome this issue, a 4 vol% TiB2/TiAl-x at% V composite was successfully prepared in the Ti–Al–B–V system using the fast hot-pressing sintering method. The solid-solution V occupied the Ti sites in TiAl and generated Ti–V bonds that are stronger than the Ti–Ti bonds. The in situ nano-TiB2 particles were mainly distributed at the grain boundaries and effectively refined the grains. Furthermore, there was excellent interfacial bonding between the nano-TiB2 and the TiAl matrix. Compared to TiAl, the room- and high-temperature yield stress and ultimate compressive stress of the 4 vol% TiB2/TiAl–3V composite were greatly enhanced by the combined action of nano-TiB2 and V. At 25 °C and 600 °C, the yield stresses of the 4 vol.% TiB2/TiAl–3V composite were 1059 MPa and 876 MPa, respectively, which represent increases of 49.6% and 73.1%, respectively. The ultimate compressive stresses at the two temperatures were 2213 MPa and 1612 MPa, respectively, which represent increases of 26.1% and 11.3%, respectively.