V和B元素对Ti-44Al-5Nb-1Mo合金显微组织及热变形机制的影响  

Effects of V and B on the Microstructure Evolution and Deformation Mechanisms of Ti-44Al-5Nb-1Mo Alloys

作　　者：李天瑞 许瑜倩 吴文平 甘文萱 杨永 刘国怀[2] 王昭东[2] LI Tianrui;XU Yuqian;WU Wenping;GAN Wenxuan;YANG Yong;LIU Guohuai;WANG Zhaodong(College of Metallurgical Engineering,Anhui University of Technology,Ma'anshan 243000,China;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]安徽工业大学冶金工程学院,马鞍山243000 [2]东北大学轧制技术与连轧自动化国家重点实验室,沈阳110819

出　　处：《金属学报》2024年第5期650-660,共11页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.52301028和52071065;中央高校基本科研业务费项目No.N2007007;安徽省科技厅自然科学基金项目No.2208085QE147;安徽省教育厅高校科研项目No.2022AH050333;安徽工业大学青年基金项目No.QZ202102。

摘　　要：为了探究V和B元素复合添加对β型γ-TiAl合金的显微组织和变形机制产生的影响,本工作针对Ti-44Al-5Nb-1Mo合金和Ti-44Al-5Nb-1Mo-2V-0.2B合金,进行了不同温度和应变速率条件下的高温热压缩实验,利用SEM-BSE和TEM对组织进行表征,对比分析了其变形后的显微组织,研究了添加V和B对Ti-44Al-5Nb-1Mo合金的显微组织及热变形机制的影响。结果表明,2种TiAl合金的显微组织差异较大,添加V和B可以显著改变TiAl合金对热变形的敏感性。Ti-44Al-5Nb-1Mo-2V-0.2B合金高温变形能力明显优于Ti-44Al-5Nb-1Mo合金。Ti-44Al-5Nb-1Mo合金的高温热变形以难变形片层团的偏转、变形带的产生为主,温度为1250℃时,其变形组织表现出较高的温度和应变速率敏感性,极易形成尺寸不均匀的近片层组织;对于Ti-44Al-5Nb-1Mo-2V-0.2B合金而言,升高变形温度或降低应变速率,既可以促进片层团内部的变形诱导L(α/γ)→α+γ+β/B2和γ→α相变,又可以促进α和β/B2相的球化/动态再结晶,从而大幅提高该合金的组织均匀性。基于变形参数对组织的影响规律,确定了控制Ti-44Al-5Nb-1Mo和Ti-44Al-5Nb-1Mo-2V-0.2B合金中近全片层、近双态显微组织的方法。TiAl alloys are considered potential structural materials because of their low density,good high-temperature strength,and creep resistance.However,their low-temperature brittleness and poor high-temperature workability lead to narrow processing windows,which hinder their industrial applications,low pressure turbine blades of high-performance engines and thermal protection system for hyper-sonic space vehicles,for instance.Extensive studies on alloying and hot mechanical processes have been conducted to control the microstructure and then enhance the inherent ductility of TiAl alloys.Alloying is considered as an effective method to stabilize softening phases or refine grains to optimize microstructural homogeneity and hot workability.Thus,β-solidifyingγ-TiAl alloys represented by Ti-(40-45)Al-(2-8)Nb-(1-8)(Cr,Mn,V,Mo)-(0-0.5)(B,C)(atomic fraction,%)alloys were designed.Nb and Mo are added asβ-phase stabilizers.Meanwhile,B,C,and Y serve as grain refiners,and they are added to increase the hot workability.However,multiple phases,precipitation,and corresponding phase transformations are introduced,leading to complex flow localization and deformation incompatibility.Therefore,considerable effort has been exerted on thermo-mechanical processing to improve the microstructural homogeneity of these alloys.The interaction among work hardening,recovery,recrystallization,and multiphase transformation under different deformation conditions easily aggravates flow localization and deformation incompatibility,which are inadequately studied.Therefore,a comprehensive understanding of the deformation behavior among multiphaseβ-solidifyingγ-TiAl alloys is necessary.In this work,the uniaxial hot compressions of theβ-solidifyingγ-TiAl alloys with the nominal compositions of Ti-44Al-5Nb-1Mo and Ti-44Al-5Nb-1Mo-2V-0.2B were conducted.The microstructure of the alloys under different temperatures and strain rates was contrastively studied using SEM-BSE and TEM.The effects of V and B on the microstructural evolutions and deformation

关 键 词：TIAL合金 (V B)合金化 热变形 显微组织 

分 类 号：TG146[一般工业技术—材料科学与工程]