High-resolution nondestructive evaluation at the center for materials diagnosis

The paper will give a brief overview on techniques that have been developed or are in progress for high resolution characterization of materials at the Center for Materials Diagnostics, University of Dayton. Acoustic microscopy is used to characterize coating systems and localized defects like corrosion pits. Significantly higher resolution is provided by Ultrasonic force microscopy, which allows the imaging of elastic inhomogenities in materials for example, studying nano-grain structures in copper films and nano precipates in aluminum alloys. Several optical high-resolution techniques have been developed or are in progress. These include interferometric imaging of the response of acoustic MEMS transducers, imaging of acoustic wave structures and early detection of crack initiation. Microellipsometric and NSOM imaging techniques are in development for imaging of surface structures significantly smaller than the optical wavelength. White light interference microscopy is frequently used to characterize surface topography with nanometer resolution for example, to quantify fretting damage or stress fields in front of fractures.