Quantitative evaluation of scale-parameter on material properties by an ultrasonic micro-spectrometer with a high apatial resolution

为了研究与材料性能相关的尺度参数，研制了一种具有高空间分辨率的超声微谱仪。本文所开发的超声光谱分析方法有望用于材料表面小区域的超声光谱表征。研究结果表明：1)在10 ~ 150 Mhz的频率范围内，UMSM可以精确测量材料在小范围内的反射系数；(2)利用测量到的反射系数可以精确地确定声表面波的相速度和衰减系数，这与材料的力学和电学性能密切相关。从表面波速和衰减量分别定量估计材料的弹性特性和晶粒尺寸，并从反射系数中检测材料的各向异性；(3)提出了一种基于超声反射率测量的反演技术，用于定量估计基底上涂膜的弹性性能。这种反演使我们能够确定具有随机分散夹杂物的薄膜复合材料的材料性质；(4)提出了液-多晶界面平均反射系数，用于定量估计非均匀材料的平均性能，并对其进行了实验和数值验证。结果表明，本文所定义的平均反射系数可作为估计非均匀材料和多晶材料局部平均性能的有用参数。平均反射系数也可以有效地估计材料弹性性能的尺度参数。由于在反射率测量中的空间分辨率和频率特性可以很容易地通过重建UMSM得到改善，因此在不久的将来可以进行有效的尺度参数估计测量。少

An ultrasonic micro-spectrometer (UMSM) with a high spatial resolution was developed in order to evaluate scale-parameters which are related to material properties. The UMSM developed here is expected to be useful for the materials characterization by ultrasonic spectroscopy at a small area on the materials surface. The results obtained in this work are summarized as follows :1) The UMSM enables us to measure precisely the reflection coefficients of materials at a small area in the frequency range from 10 to 150 Mhz ; (2) Using the measured reflection coefficients we can precisely determined phase velocities and attenuation factors of acoustic surface waves which are closely related to mechanical and electrical properties of materials. Elastic properties and grain size of materials are quantitatively estimated from the surface wave velocities and the attenuations, respectively, and also anisotropy can be detected from the reflection coefficients ; (3) An inversion technique based on th … More e ultrasonic reflectivity measurement was proposed for quantitatively estimating elastic properties of caoting films on substrate. This inversion enables us to determined materials properties of the thin film composite with randomly dispersed inclusions ; (4) Mean reflection coefficients on liquid-polycrystals interface are newly proposed for quantitatively estimating mean properties of inhomogeneous materials, and are examined experimentally and numerically. It was confirmed that the mean reflection coefficient defined here should be available as a useful parameter for estimating the local average properties in inhomogeneous materials as well as polycrystalline materials. The scale parameter on elastic properties of materials may also be estimate effectively by the mean reflection coefficient.Because the spatial resolution and frequency characteristic in the reflectivity measurements can easily be improved by reconstructing the UMSM,efficient measurements for estimating the scale parameter will be performed in near future. Less