Improving thermal stability and creep resistance by Sc addition in near-αhigh-temperature titanium alloy  

作　　者：Xiuyang Zhong Tongsheng Deng Wenlong Xiao Xiaochun Liu Zhi Liu Yucheng Yang Olanrewaju A.Ojo 

机构地区：[1]Faculty of Materials Metallurgy and Chemistry,Jiangxi University of Science and Technology,Ganzhou 341000,China [2]School of Materials Science and Engineering,Beihang University,Beijing 100191,China [3]Institute of Metals,College of Materials Science and Engineering,Changsha University of Science&Technology,Changsha 410004,China [4]Department of Mechanical Engineering,University of Manitoba,Winnipeg,MB R3T 5V6,Canada

出　　处：《Journal of Materials Science & Technology》2024年第16期1-11,共11页材料科学技术（英文版）

基　　金：The authors acknowledge financial support from the Jiangxi Provincial Natural Science Foundation(No.20224BAB204043);Ganzhou Science and Technology Planning Project([2019]No.60);the Graduate Innovation Special Fund Project of Jiangxi Province in 2022(No.YC2022-S655).

摘　　要：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-6.5A1-2.5Sn-9Zr-0.5Mo-1Nb-1W-0.3Si-xSc(x,0-0.5 wt.%)at 650°C.The lamellar secondaryαphase is refined and the formation of Sc_(2)O_(3)is increased with the increasing scandium(Sc)additions,which im-proves the strength of the alloy,while excessive Sc_(2)O_(3)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 Ti3 Al phase and improving the thermal stability of the alloy.Meanwhile,Sc accelerates the dissolution of the residualβphase 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 secondaryαphases,Sc_(2)O_(3)particles,Ti3 Al phase,and silicides,especially the precipitated silicides.Eventually,the 0.3 Sc alloy shows optimal ther-mal stability(the plasticity loss rate 17.3%)and creep resistance(steady-state creep rate 4.4×10^(-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).

关 键 词：Titanium alloy CREEP Microstructure SILICIDE SCANDIUM 

分 类 号：TG146.23[一般工业技术—材料科学与工程]