摘要
利用团簇成分式方法设计系列低密度Co基高温合金[Al-(Co_(8)Ni_(4))]((Al_(0.5)(Ti/Nb/Ta)_(0.5)Mo_(0.5))(Mo_(0.5)Cr_(0.5)Co_(0.5)))(=Co_(8.5)Ni_(4)Al_(1.5)Mo_(1.0)Cr_(0.5)(Ti/Nb/Ta)_(0.5)),采用真空非自耗电弧炉制备合金铸锭,并对其在1300℃固溶15 h,在900℃下进行长期时效处理,进而对时效态样品进行微观组织表征和力学性能测试.结果表明,当Ti/Nb/Ta,Ti/Nb和Ti/Ta以等物质的量比匹配时,3种合金的微观组织均表现为立方形γ′相均匀地分布在γ基体中,这取决于合金适中的γ/γ′点阵错配度(0.27%—0.34%).在900℃长期时效过程中,3种合金中的γ′相均具有较小的粗化速率,且合金的显微硬度随时效时间基本不发生变化(275—296 HV);尤其(Ti/Ta)_(0.5)合金具有最高的γ/γ′共格组织稳定性,时效500 h后γ′相粗化最慢,并在晶界处无其他第二相粒子析出,而在其他合金的晶界附近均析出针状和颗粒状的第二相粒子.
Co-base superalloys generally have high strengths,good oxidation-and corrosion-resistances,as well as excellent creep-resistant properties at high temperatures(HTs),which are ascribed to the coherent precipitation of cuboidalγ′phase into face-centered-cubic(FCC)γmatrix induced by co-alloying of multiple elements.However,the cuboidalγ/γ′coherent microstructure is liable to be destabilized after a long-time aging at HTs in Co-base superalloys.In the present work,the cluster formula is used to design a series of low-density Co-base superalloys with the composition of[Al-(Co_(8)Ni_(4))]((Al_(0.5)(Ti/Nb/Ta)_(0.5)Mo_(0.5))(Mo_(0.5)Cr_(0.5)Co_(0.5)))(=Co_(8.5)Ni_(4)Al_(1.5)Mo_(1.0)Cr_(0.5)(Ti/Nb/Ta)_(0.5)).Alloy ingots are prepared by are melting under an argon atmosphere,and are solid-solutionized at 1300℃for 15 h and then aged at 900℃for up to 500 h.Microstructural characterizations and mechanical properties of these alloys in different aged states are obtained by using XRD,SEM,EPMA,TEM,and HV.It is found that all these alloys with Ti/Nb/Ta,Ti/Nb,and Ti/Ta in an equi-molar mixing have a special coherent microstructure with cuboidalγ′phase uniformly-precipitated into theγmatrix,which is contributed to the moderate lattice misfit ofγ/γ′(0.27%-0.34%).Moreover,these cuboidalγ′phase are coarsened slowly during aging,in which the microhardness does not vary obviously with aging time(275 HV-296 HV).Especially,the alloy with(Ti/Ta)_(0.5)exhibits the highestγ/γ′microstructural stability with a slow coarsening rate after aging 500 h,and no other second phases appear near the grain boundaries.While needle and bulk particles would precipitate on grain boundaries in other alloys after 500 h-aging.
作者
吕梦甜
李金临
孙九栋
王镇华
王清
董闯
LüMeng-Tian;Li Jin-Lin;Sun Jiu-Dong;Wang Zhen-Hua;Wang Qing;Dong Chuang(Key Laboratory of Materials Modification by Laser,Ion and Electron Beams,Ministry of Education,Dalian University of Technology,Dalian 116024,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第11期356-365,共10页
Acta Physica Sinica
基金
国家自然科学基金(批准号:91860108,U1867201)
大连市科技创新基金重点学科(研究方向)和重大课题(批准号:2020JJ25CY004)资助的课题.
关键词
Co基高温合金
/共格组织
/γ′相粗化
/第二相析出
Co-base superalloys
coherent microstructure
γ′phase coarsening
the second precipitated phases
