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

High temperature compression properties and microstructure of two Ti-Al bas ed alloys with and without Sc were studied The results show that minor addi tion may remarkably improve the high temperature yield strength of Ti-Al an d Ti-48Al based alloy which have either duplex structure or full lamellar s tructure, the yield strength increment is 120 and 125 MPa, respectively. Mi nor Sc exists as Ti-3(Al,Sc) in plate precipitates which distribute mainly along with alpha(2)/gamma or gamma/gamma(T), boundaries, partly within gamm a phases. At high temperature, deformation of gamma phases is easier than t hat in the alpha(2) phase, the deformation mode is dislocation slipping. Th e obstacle to interlamellar sliding and dislocation slipping caused by Ti-3 (Al, Sc) precipitates should be responsible For yield strength increment of Ti-Al alloys with Sc. Published by Elsevier Science S.A.