Ultrasonic Attenuation Peak during Creep of a Nickel-Base Superalloy with Electromagnetic Acoustic Resonance
Ultrasonic Attenuation Peak during Creep of a Nickel-Base Superalloy with Electromagnetic Acoustic Resonance
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电磁声谐振镍基高温合金蠕变过程中的超声衰减峰
DOI：
10.2472/jsms.53.692
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
M. Hirao
中科院分区：
文献类型：
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作者：
T. Ohtani;H. Ogi;M. Hirao
电磁声共振（EMAR）是一种利用电磁声换能器（EMAT）进行非接触共振的方法。这种方法没有额外的能量损失，导致测量固体中的固有超声衰减。本研究将EMAR应用于一种镍基高温合金（Waspaloy）的蠕变损伤检测。将材料暴露在1073K的不同应力下。随着蠕变的推进，我们测量了1-6 mhz频率范围内的超声波衰减。衰减系数对损伤累积的敏感性远高于速度。在较短的时间间隔内，在全寿命的35% ~ 40%之间，衰减出现一个较大的峰值，超声速度出现一个较小的下降，与应力无关。这种新现象被解释为微观结构变化，特别是位错迁移的结果。位错结构的透射电镜观察也证实了这一点。该技术在评估金属的损伤进程和预测金属的蠕变寿命方面具有一定的潜力。
Electromagnetic acoustic resonance (EMAR) is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method is free from extra energy losses, resulting in the measurement of intrinsic ultrasonic attenuation in solids. In this study, the EMAR was applied to detect the creep damage of a Ni-base superalloy (Waspaloy). The material was exposed to the temperature of 1073K at various stresses. We measured ultrasonic attenuation for 1-6-MHz frequency range as the creep advanced. The attenuation coefficient exhibits much larger sensitivity to the damage accumulation than the velocity. In a short interval, between 35% and 40% of whole life, attenuation experiences a large peak and ultrasonic velocity shows a small depression, being independent of the stress. This novel phenomenon is interpreted as resulting from microstructure changes, especially, dislocation mobility. This is supported by TEM observations for dislocation structure. This technique has a potential to assess the damage advance and to predict the creep life of metals.