Tensile properties of a newly developed high-temperature titanium alloy at room temperature and 650 degrees C

Abstract

Commonly used high-temperature near-alpha titanium alloys contain Al, Zr and Si as their alloying elements. Significant losses of mechanical properties and cleavage mode failures are evident due to the presence of Ti3Al and S2 types of zirconium silicides ((TiZr)6Si3) in these alloys. We developed a new alloy (Ti-6.5Al-3.0Sn-4.0Hf-0.2Nb-0.4Mo-0.4Si-0.1B) by replacing Zr with Hf to avoid the formation of zirconium silicides. Aging at 700 degrees C for five hours successfully eliminated the Ti3Al phase and substantially improved the room-temperature ductility. Tensile tests were carried out at room temperature and at 650 degrees C. The mechanical properties of the present alloy were significantly improved compared to those of existing high-temperature titanium alloys under testing at ambient and elevated temperatures.