Development of A Novel Resonance Ultrasound Microscopy and Absolute Measurement of Local Elastic Constant of Micro and Nano Composites

发展了共振超声显微术，用于定量测定微纳米复合固体的弹性常数和局部区域的内耗。它包括一个无线和无电极的硅酸镓振荡器，这是由位于振荡器附近的线天线以非接触的方式驱动。因此，振荡器的非接触激励和检测成为可能。振动分析准确地确定了振荡器的节点，在该节点处振荡器被支撑，使得振荡器与除了通过金刚石尖端在振荡器的底表面上的波腹点处的接触样本之外的任何其他声学接触隔离。因此，振荡器是声学隔离的，这使我们能够从谐振频率变化确定接触材料的模量。进行振动分析，以确定由共振频率的接触材料的有效模量。显微镜被应用到双相不锈钢，多晶铜，和NbTi/Cu复合材料。测量的有效杨氏模量显示出良好的协议与预测值。此外，它表明，这种显微镜是有用的材料的无损评价。进行蠕变试验的铜试样用于该检查。共振超声显微镜显示了铜试样的损伤组织。在晶界附近观察到由蠕变空洞引起的软化区域。此外，晶粒内部的弹性常数减小，表明软化不仅发生在晶界附近，而且发生在晶粒内部。

Resonance ultrasound microscopy has been developed for quantitatively determining the elastic constant and internal friction of local region of micro and nano composite solids. It includes a wireless and electrodeless langasite oscillator, which was driven by a noncontacting manner by the line antenna located near the oscillator. Thus, the noncontacting excitation and detection of the oscillator was made possible. The vibrational analysis determined accurately the nodal points of the oscillator, at which the oscillator was supported, making the oscillator isolated from any other acoustical contacts except for the contacting specimen at the antinode spot on the bottom surface of the oscillator through a diamond tip. Thus, the oscillator was acoustically isolated, which allowed us to determine the modulus of the contacting material from the resonance frequency change. The vibrational analysis was made to determine the effective modulus of the contacting material from the resonance frequency. The microscopy was applied to duplex stainless steels, polycrystalline copper, and NbTi/Cu composites. The effective Young modulus measured showed good agreement with the values predicted. Also, it was shown that this microscopy was useful for the nondestructive evaluation of materials. The copper specimen subjected to the creep test was used for this examination. The resonance ultrasound microscopy visualized the damaged microstructure of the copper specimen. The softened regions were observed near the grain boundaries, caused by the creep voids. Besides, the elastic constant decreased inside the grains, indicating that the softening occurred not only near the grain boundaries but also inside the grains.