Research on Nondestructive Material Characterization with Multi-function Acoustic Microscope System

将点聚焦束(PFB)成像、线聚焦束(LFB)定量测量和定向PFB显微镜系统三种系统功能相结合，为材料表征提供了一种新的研究工具。为了验证复杂信号下的成像性能，对熔融石英板进行了幅值和相位模式的成像。同时测量了样品表面的幅值和位相图像，定量分析了样品表面形貌的对比度。在含有部分磁畴反转区域的LiTaO_3晶片成像中，尽管弹性性质相同，但在磁区边界观察到了对比度。结果表明，这种对比度是由于电学性质不同而产生的反射漏表面声波(LSAW)引起的。利用定向PFB声学装置对表面有垂直裂纹的氧化镁晶体进行了成像。对平均晶粒度为100μm的纯钛和锰锌铁氧体多晶样品进行了研究，在225MHz处获得了不同传播方向的声场定向图像。通过V(Z)曲线分析，测量了样品中某些颗粒的直缝埋弧焊速度的各向异性，并从成像和定量测量两个方面表征了每个颗粒的各向异性弹性性质。

A multi-function acoustic microscope system combined three system functions of imaging by point-focus-beam (PFB), quantitative measurement by line-focus-beam (LFB) and directional PFB microscope system with two functions of imaging and quantitative measurements has been developed as a new research tool for material characterization.To confirm the imaging perfomance with complex signals, imaging for fused quartz plates formed topographic lattice patterns were made with both amplitude and phase modes. Contrasts of topographic shapes on the specimen surface have been analyzed quantitatively by measuring amplitude and phase images simultaneously.In imaging of LiTaO_3 wafer with partially domain-inverted regions, contrast was observed at domain boundary in spite of same elastic properties. It has been showed that such contrast was caused by reflecting leaky surface acoustic wave (LSAW) due to difference of electrical properties at the domain boundary.The directional PFB acoustic device was applied for imaging of an MgO crystal with vertical cracks on the surface. The spaces of fringes produced in parallel to cracks were different in propagation directions of LSAWs.It has been proved that LSAW velocity of each direction could be characterized quantitatively.The system has been demonstrated for investigation of polycrystalline samples of pure Ti and Mn-Zn ferrite with average grain size of 100μm. Directional acoustic images were obtained at 225 MHz for several different propagation derections of LSAWs. Anisotropy measurements of LSAW velocity in some grains of the samples have been perfomed through V(z) curve analysis.Anisotropic elastic properties of each grain have been characterized both in imaging and quantitative measurements.