Effect of Rare Earth Er on the Microstructure and Mechanical Properties of High Temperature Titanium Alloys

摘要

The microstructures and mechanical properties of the high temperature titanium alloys containing Er, i.e. Ti-6Al-2.5Sn-4Zr-0.3Mo- lNb-0.35Si-xEr (x=0, 0.1, 0.3wt%), were investigated. Both the grain size and lamellar structure inside grains were significantly refined with the addition of Er in as-cast alloys. Lamellar and duplex microstructures were obtained after forging and heat treatment. Silicide precipitates were generated in the boundary of lamellar a phase after aging treatment. Meanwhile, a few a_2 phase were precipitated in the alloys after aging treatment. After 600℃ /100h thermal exposure, the a_2 phases with a mean size of 7nm and spacing of 10 nm were precipitated homogeneously in a lamellar. The creep properties were significantly improved by the addition of rare earth Er due to the formation of the second phase containing Er, silicide and a_2 phase.