Real-Time Observation of Dislocation under Stress using Laser-induced Ultrasonic Waves

使用激光诱导超声波实时观察应力下的位错

• 批准号: 11650060
• 负责人: CHOI Pak-Kon
• 金额: $ 2.3万
• 依托单位: Meiji University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650060/
• 关键词: 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

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.

1999年，我们开发了激光耗竭的实验系统，该系统采用了高功率脉冲激光器来激发超声波，以及共焦型Fabry-Perot干涉仪来检测超声波波。使用90％反射率的干涉仪的镜子检测到含有2-30 MHz成分的超声波脉冲波。液的金属含量是在与液态金属接触时通常会压力的延长延伸到失败的伸长率减少。我们通过使用激光诱导的超声测量雷利波速度和衰减，在铝合金中具有易非固定的凝胶渗透过程。衰减测量结果显示了两个阶段的穿透过程：快速的速度沿表面形成一个结构，速度为28μm/s，较慢的速度是均质渗透到整体中。速度显示随时间演变的下降，反映了较慢的阶段。纵向和剪切波测量结果表明，较慢的散装渗透到合金中。表面穿透过程比散装渗透过程快得多的事实可能是由于合金产品过程中引入的残留应力引起的。这促进了瑞利波速度的方向依赖性（即各向异性）的测量。结果表明，各向异性为0.25％，阐明了表面穿透速度的各向异性。使用拉伸应力设备的瑞利波速度的应力依赖性正在进行中。

项目成果

R.Tanaka,P-Kchui,H.Koizumi,S.Hyodo: "Fast penetration of liquid gallium in polycrystalline aluminum films"Materials Transactions. 42(1). 138-140 (2001)

R.Tanaka，P-Kchui，H.Koizumi，S.Hyodo：“液态镓在多晶铝薄膜中的快速渗透”材料交易。