Effect of minor Sc on high temperature mechanical properties of Ti–Al based alloys

High temperature compression properties and microstructure of two Ti–Al based alloys with and without Sc were studied The results show that minor addition may remarkably improve the high temperature yield strength of Ti–Al and Ti–48Al based alloy which have either duplex structure or full lamellar structure, the yield strength increment is 120 and 125 MPa, respectively. Minor Sc exists as Ti3(Al,Sc) in plate precipitates which distribute mainly along with α2/γ or γ/γT boundaries, partly within γ phases. At high temperature, deformation of γ phases is easier than that in the α2 phase, the deformation mode is dislocation slipping. The obstacle to interlamellar sliding and dislocation slipping caused by Ti3(Al, Sc) precipitates should be responsible for yield strength increment of Ti–Al alloys with Sc.