Cr/Mo/W元素对镍基高温合金γ/γ′共格组织热稳定性的影响  

Effect of Cr/Mo/W on the Thermal Stability of γ/γ′Coherent Microstructure in Ni-Based Superalloys

作　　者：凡莉花 李金临 孙九栋 吕梦甜 王清[1] 董闯[1] FAN Lihua;LI Jinlin;SUN Jiudong;LV Mengtian;WANG Qing;DONG Chuang(Key Laboratory of Materials Modification by Laser,Ion and Electron Beams(Ministry of Education),School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学材料科学与工程学院三束材料改性教育部重点实验室,大连116024

出　　处：《金属学报》2024年第4期453-463,共11页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.91860108;大连市科技创新基金重点学科(研究方向)和重大课题项目No.2020JJ25CY004。

摘　　要：近年来,随着航空航天发动机的持续发展,对其关键热端部件的承温能力要求越来越高,而高温合金共格组织热稳定性是影响其力学性能的关键因素,本工作在团簇成分式[Al-Ni_(12)](Al_(1)(Ti,Nb,Ta)_(0.5)(Cr,Mo,W)_(1.5))基础上,保持其他元素含量不变,改变Cr、Mo、W的含量设计了系列镍基高温合金(含Cr_(1.0)Mo_(0.5)的S1-CM、Cr_(1.0)W_(0.5)的S2-CW和含Cr_(0.7)Mo_(0.4)W_(0.4)的S3-CMW),研究Cr、Mo、W含量变化对合金γ/γ′共格组织热稳定性的影响。采用非自耗真空电弧炉制备合金铸锭,并对其在1300℃固溶15 h后在900℃下进行长期时效处理,并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,这3个合金的微观组织均表现为高体积分数(f>70%)的γ′粒子均匀地分布在fcc-γ基体中。其中,S1-CM和S2-CW合金在900℃、50 h时效后γ′粒子形貌均呈椭球形,而S3-CMW合金则表现为方形,这是由于后者具有更负的γ/γ′点阵错配度(后者δ=-0.47%,前者δ=-0.25%~-0.33%)。500 h长期时效后,各合金中的γ′粒子形貌没有发生变化,且都具有较慢的粗化速率(K=10~18 nm^(3)/s);尤其S3-CMW合金表现出最高的γ/γ′共格组织稳定性(γ′粒子的粗化速率K=10.02 nm^(3)/s),且晶界处的第二相粒子析出明显低于其他合金。系列合金的硬度基本不随时效时间发生变化,也进一步表明了共格组织的稳定性;其中S3-CMW合金的显微硬度为397~418 HV,时效200 h后的室温压缩屈服强度为818 MPa。In general,Ni-based superalloys exhibit high strength,good oxidation and corrosion resistance,and good creep-resistant properties at high temperatures(HTs)because of the coherent precipitation of cuboidal γ′nanoparticles into a fcc-γmatrix induced by co-alloying of multiple elements.The present work designed a series of Ni-based superalloys based on the cluster composition formula[Al-Ni_(12)](Al_(1)(Ti,Nb,Ta)_(0.5)(Cr,Mo,W)_(1.5)),with S1-CM(Cr_(1.0)Mo_(0.5)),S2-CW(Cr_(1.0)W_(0.5)),and S3-CMW(Cr_(0.7)Mo_(0.4)W_(0.4)),in which the amounts of Cr,Mo,and W were changed,whereas the contents of other elements were maintained.In addition,the effect of Cr,Mo,and W variation on the thermal stability of γ/γ′coherent microstructure at HT in these superalloys was investigated.Alloy ingots were prepared by arc melting under an argon atmosphere,solid solutionized at 1300℃ for 15 h,and then aged at 900℃ for up to 500 h.Microstructural characterization and mechanical properties of these alloys in different aged states were studied by XRD,SEM,EPMA,TEM,Vickers hardness testing,and compressive testing.Result showed that all these three alloys have a high volume fraction(f>70%)of γ′particles uniformly distributed in the fcc-γ matrix.In particular,the γ′particle shape is ellipsoidal in S1-CM and S2-CW alloys,whereas it is cuboidal in the S3-CMW alloy primarily because the latter has a more negative γ/γ′lattice misfit(d=−0.47%)than the former(δ=-0.25% to -0.33%).After aging for 500 h,the morphology of γ′particles in each alloy has no evident change,and all of the particles have a slow coarsening rate(K=10-18 nm^(3)/s),in which the S3-CMW alloy exhibits the highest γ/γ′microstructural stability(the coarsening rate of γ′particles being K=10.02 nm^(3)/s).Moreover,the amount of second-phase precipitation near the grain boundaries in the S3-CMW alloy is less than that in the former two alloys.The microhardness test results showed that the microhardness of each alloy remains almost constant with aging tim

关 键 词：镍基高温合金 共格组织 γ′粒子粗化 第二相析出 

分 类 号：TG113.12[金属学及工艺—物理冶金]