Abstract
High-temperature titanium alloys'thermal stability and creep resistance are significant during service in high temperatures.This study systematically investigated the thermal stability and mechanical properties of Ti-6.5Al-2.5Sn-9Zr-0.5Mo-1Nb-1W-0.3Si-xSc(x,0-0.5 wt.％)at 650 ℃.The lamellar secondary α phase is refined and the formation of Sc2O3 is increased with the increasing scandium(Sc)additions,which im-proves the strength of the alloy,while excessive Sc2O3 becomes the crack source and deteriorates the plasticity.The oxygen content in the matrix is reduced by the interaction between Sc and oxygen,in-hibiting the growth of the Ti3Al phase and improving the thermal stability of the alloy.Meanwhile,Sc accelerates the dissolution of the residual β phase and precipitation of fine,diffusely distributed ellip-soidal silicides,which strongly prevents dislocation movement.The enhancement of creep resistance for the Sc-containing alloy is attributed to the refined lamellar secondary α phases,Sc2O3 particles,Ti3Al phase,and silicides,especially the precipitated silicides.Eventually,the 0.3Sc alloy shows optimal ther-mal stability(the plasticity loss rate 17.3％)and creep resistance(steady-state creep rate 4.4 x 10-7 s-1).The investigation results provide new insights into the mechanism and thermal stability improvement in high-temperature titanium alloys modified by rare earth(RE).
基金项目
Jiangxi Provincial Natural Science Foundation(20224BAB204043)
Ganzhou Science and Technology Planning Project([2019]60)
Graduate Innovation Special Fund Project of Jiangxi Province in 2022(YC2022-S655)
NETL
NSTL
万方数据