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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第31卷    第7期    总第268期    2021年7月

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文章编号:1004-0609(2021)-07-1747-10
90W-Ni-Fe合金在应变率6000 s-1不同应变条件下的微观组织
张 磊,黄宇峰,陈 逊,刘文胜,马运柱

(中南大学 轻质高强结构材料国家级重点实验室,长沙 410083)

摘 要: 通过分离式霍普金森杆(SHPB)和应变限位环方法实现90W-Ni-Fe合金在应变率6000 s-1不同应变条件下(0.15、0.25、0.45、0.6)的动态变形,并利用扫描电子显微镜(SEM)、透射电子显微镜(TEM),电子背散射衍射(EBSD)技术及纳米压痕技术对变形后钨颗粒的微观组织及力学性能进行表征。结果表明:应变低于0.25,钨颗粒主要发生均匀塑性变形,位错滑移是其变形的主要机制;当应变达到0.45时,冲击过程中的温升加速钨颗粒内位错的重排和湮灭,导致钨颗粒内部发生动态回复,形成大量板条状的亚晶粒;当应变达到0.6时,试样内部形成绝热剪切带,其内部组织主要由大量细小的等轴晶组成。晶粒细化导致剪切带内的硬度(13.21 GPa)高于剪切带外的硬度(9.16 GPa)。随着应变的继续增加,微裂纹在剪切带内形核和扩展,导致90W-Ni-Fe合金断裂失效。

 

关键字: 钨合金;动态载荷;应变;绝热剪切

Microstructural characteristic of 90W-Ni-Fe alloy at strain rate of 6000 s-1 and different strains
ZHANG Lei, HUANG Yu-feng, CHEN Xun, LIU Wen-sheng, MA Yun-zhu

National Key Laboratory of Science and Technology for National Defense on High-strength Structural Materials, Central South University, Changsha 410083

Abstract:The dynamic deformation of 90W-Ni-Fe alloy at the strain rate of 6000 s-1 and different strains (0.15, 0.25, 0.45, 0.6) was obtained by using the Split Hopkinson pressure bar (SHPB) system and strain stopping rings. Scanning electron microscope (SEM), transmission electron microscope (TEM), electron backscattering diffraction (EBSD) and nano-indentation technique were used to analyze the microstructure characteristics and mechanical properties of the deformed tungsten particles. The results show that homogeneous plastic deformation mainly occurs in the tungsten particles when the strain is lower than 0.25 and the dislocation slip is proposed as the primary deformation mechanism of tungsten alloy. As the strain level increases to 0.45, the temperature rise during the impact process accelerates the dislocation rearrangement and annihilation of tungsten particles, leading to the dynamic recovery occurs in the tungsten particles and the formation of a large number of lath subgrains. As the strain level increases to 0.6, an adiabatic shear band is formed in the specimen, the microstructure in adiabatic shear band is mainly comprised of numerous fine small grains. Grain refinement causes the nano-hardness inside the shear band (13.21 GPa) to be higher than that outside the shear band (9.16 GPa).With the strain increasing, the microcracks nucleate and expand along the shear band, resulting in the failure of 90W-Ni-Fealloy.

 

Key words: tungsten alloy; dynamic loading; strain; adiabatic shear

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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