Ti_(2)AlNb合金等温多向锻造板条O相球化行为和硬化机制研究  

Spheroidization Behavior and Hardening Mechanism of the Lath Ti_(2)AlNb Alloy During Multi-directional Isothermal Forging

作　　者：李萍[1] 黄晓雨 刘乐 郭胜华 薛克敏[1] Li Ping;Huang Xiaoyu;Liu Le;Guo Shenghua;Xue Kemin(School of Materials Science and Engineering,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]合肥工业大学材料科学与工程学院,安徽合肥230009

出　　处：《稀有金属材料与工程》2023年第2期685-691,共7页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51975175,51875158)。

摘　　要：在800℃下对Ti_(2)AlNb合金进行等温多向锻造,采用SEM、XRD、EBSD和硬度测试等定量分析了不同变形道次下合金微观组织和显微硬度的变化规律,揭示了板条O相的动态球化行为和合金硬化机制。结果表明:随变形道次的增加,初始粗大板条O相先后经历了动态机械破碎和动态再结晶2种细化机制,板条完全球化主要发生在3道次变形过程中;板条O相的动态球化过程伴随着弯曲、扭折、剪切和晶粒撕裂这4种变形行为,后2类变形的机制可概括为:O/O相界分离、B2相嵌入、O相分离和O相球化;3道次变形后初始板条O相细化至1.3μm的等轴组织,细小等轴O相含量高达68.84%,此时合金硬度较初始样提高了103.55HV(1014.79 MPa),晶界硬化机制的贡献占比为64%。Multidirectional isothermal forging(MIF) experiments of Ti_(2)AlNb alloy was carried at 800 ℃. The microstructure evolution and hardness of the alloy under different deformation cycles were quantitatively analyzed by SEM, XRD, EBSD and hardness testing. The dynamic spheroidization behavior of the lath O and alloy hardening mechanism was revealed. The results show that as the number of deformation cycles increases, the initial coarse lath O has undergone two refinement mechanisms, namely dynamic mechanical breaking and dynamic recrystallization. The globalization of the lath mainly occurs in 3 cycles deformation process. The dynamic spheroidization process is accompanied by four deformation behaviors: bending, kinking, shearing and grain tearing. The mechanism of the latter two types of deformation can be summarized as: O/O phase boundary separation, penetration of B2 phase, O phase separation and O phase spheroidization. The initial lath O phase is refined to 1.3 μm equiaxed structure, and the percentages of fine equiaxed O phase is as high as 68.84% after 3 cycles of MIF. At this time, the hardness of the alloy is 103.55HV(1014.79 MPa) higher than that of the initial sample, and the contribution of grain boundary hardening mechanism is 64%.

关 键 词：等温多向锻造 Ti_(2)AlNb合金 板条O相 动态球化行为 硬化模型 

分 类 号：TG146.23[一般工业技术—材料科学与工程] TG319[金属学及工艺—金属材料]