Formation of heterogeneous interfaces in the TiAl/Ti_(2)AlNb layered composite and its effect on the fracture toughness  

作　　者：Beibei Wei Bin Tang Xiaofei Chen Xiang Zhang Lei Zhu Jinhua Dai Biao Ma Songkuan Zhao Jinshan Li 

机构地区：[1]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an,710072,China [2]Chongqing Innovation Center,Northwestern Polytechnical University,Chongqing,401135,China [3]Shaanxi Key Laboratory of Electrical Materials and Infiltration Technology,School of Materials Science and Engineering,Xi’an University of Technology,Xi’an,710048,China

出　　处：《Journal of Materials Science & Technology》2024年第34期58-74,共17页材料科学技术(英文版)

基　　金：supported by the National Key Re-search and Development Program of China(No.2021YFB3702603);the Innovation Foundation for Doctor Dissertation of Northwest-ern Polytechnical University(No.CX2023045);the National Nat-ural Science Foundation of China(No.52174377);Chongqing Technology Innovation and Application Development Project(No.CSTB2022TIAD-KPX0032);the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2022-TS-06).

摘　　要：TiAl/Ti_(2)AlNb intermetallic-intermetallic laminated(IIL)composites featuring brittle/ductile heterogeneous interfaces were fabricated through vacuum hot-pack rolling.The microstructures and the phase transfor-mation behaviors of the interfaces of the IIL composites before and after annealing at 900°C/6 h were in-vestigated.The heterogeneous interfaces are composed of four distinct regions,individually I(β_(o)+γ+α_(2)),II(β_(o)/B_(2)+ω)(brittle part),III(O lath),and IV(equiaxed O)(ductile part)regions from TiAl to Ti_(2)AlNb side.Notably,after annealing,an equiaxed O band approximately 50μm wide was observed in region IV of the interface.In addition,a significant microhardness variation was observed between regions II and IV of the interface,where region II exhibited higher hardness compared to the TiAl alloy,and region IV displayed lower hardness than the Ti_(2)AlNb alloy.The enhanced fracture toughness of the IIL composites,three times that of the TiAl base alloy,is attributed to the formation of the brittle/ductile heterogeneous interfaces and the layered design incorporating the Ti_(2)AlNb alloy.The corresponding toughening mech-anism was further discussed.The brittle II region plays a role in increasing crack branching,while the ductile IV region inhibits the propagation of microcracks and prevents the formation of main cracks.This work highlights the crucial role of the brittle/ductile heterogeneous interface in the toughening of lam-inated composites.Furthermore,the discovery of the O band provides novel insights into the design of TiAl/Ti_(2)AlNb heterostructures.

关 键 词：TiAl/Ti_(2)AlNb laminated composites Heterogeneous interfaces Phase transformation MICROHARDNESS Fracture toughness 

分 类 号：TG1[金属学及工艺—金属学]