| Project/Area Number |
11650060
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied physics, general
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| Research Institution | Meiji University |
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Principal Investigator |
CHOI Pak-Kon Dept. of Physics, Meiji University, Professor, 理工学部, 教授 (30143530)
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| Co-Investigator(Kenkyū-buntansha) |
KOIZUMI Hirokazu Dept. of Physics, Meiji University, Professor, 理工学部, 教授 (60126050)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | laser ultrasonics / liquid-metal embrittlement / Rayleigh wave / aluminum alloy / gallium / 表面波 / レーザ超音波 / レーザー超音波 / 超音波吸収 / ファブリ・ペロー干渉計 / パルスレーザ |
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| Research Abstract |
In 1999, we developed the experimental system of laser-ultrasound which employs a high-power pulsed laser to excite ultrasonic waves, and a confocal-type Fabry-Perot interferometer to detect the ultrasonic waves. The ultrasonic pulsed-waves containing 2-30 MHz components were detected using the mirrors of the interferometer with 90 % reflectivity.
Liquid metal embrittlement is the reduction in the elongation to failure that can be produced when normally ductile solid metals are stressed while in contact with a liquid metal such as gallium. We have studied extraordinary-fast penetration process of gallium in aluminum alloys by measuring Rayleigh-wave velocity and attenuation using laser-induced ultrasound. The results of attenuation measurements showed two-stage penetration processes : the fast one is forming a structure like a spider's web along the surface with the speed of 28 μm/s ,and the slower one is the homogeneous penetration into the bulk. The velocity showed the decrease with time evolution, reflecting the slower stage.
The longitudinal and shear waves measurements showed the slower bulk penetration into the alloy. The fact that the surface penetration process is much faster than the bulk penetration is probably caused by the residual stress that was introduced in the product process of the alloy. This promoted the measurement of direction dependence, that is anisotropy, of the Rayleigh wave velocity. The results showed the anisotropy of 0.25 %, which elucidates the anisotropy of surface penetration speed.
A stress dependence of Rayleigh wave velocity using tensile stress equipment is in progress.
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