摘要
选取定向凝固镍基高温合金DZ444不同方向片状试样,利用电子背散射衍射等技术表征晶体取向和微观组织,利用脉冲回波技术分析纵波声速和声衰减系数。结果表明:两声学特性呈各向异性,随着试样平面法向与凝固方向之间夹角φ由0°到45°再到90°,纵波声速由5533m/s增大到6595m/s后又降至5634m/s,而声衰减系数逐渐增大,变化约0.19dB/mm;对信号频谱分析发现,表面回波与一次底波的主频差值、主频幅值差值及表观积分反射系数均逐渐增大,这主要是由微观组织和晶体取向差异造成的。
Directionally solidified nickel-based superalloy DZ444 specimens with different directions were selected.The crystal orientation and microstructure were characterized by electron back-scattered diffraction technique and so on.The longitudinal wave velocity and attenuation coefficient were analyzed by ultrasonic pulse-echo technique.Results show that the above two acoustic properties are anisotropic.With the included angleφbetween the normal direction of the sheet plane and the solidified direction increases from 0°to 45°to 90°,the longitudinal wave velocity increases from 5533m/s to 6595m/s and then decreases to 5634m/s,while the attenuation coefficient shows a monotonic increment of 0.19dB/mm.Further spectrum analysis shows that the main frequency shift,amplitude shift and apparent integral reflection coefficient of the surface echo and the bottom echo present a similar trend with the attenuation coefficient.This is mainly resulted by the difference of microstructure and crystal orientation.
作者
罗忠兵
张嘉宁
金士杰
林莉
LUO Zhong-bing;ZHANG Jia-ning;JIN Shi-jie;LIN Li(NDT & E Laboratory,Dalian University of Technology,Dalian 116085,Liaoning,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2019年第4期120-126,共7页
Journal of Materials Engineering
基金
国家自然科学基金资助项目(51775087
51405061)
关键词
定向凝固
镍基高温合金
声学特性
各向异性
频谱分析
directional solidification
nickel-based superalloy
acoustic property
anisotropy
spectrum analysis
