Imaging of Microstructural Features and Local （成像的微观结构特性和地方）.pdf

5th International Workshop NDT in Progress Meeting of NDT experts, October 12 – 14, 2009 Prague, Czech Republic, Hotel and Congress center Floret Imaging of Microstructural Features and Local Stiffness of α and β Phases in Titanium Ti-6Al-4V Alloy by Atomic Force Acoustic Microscopy Jonas Rabe, Ute Rabe, Sigrun Hirsekorn Fraunhofer Institut für zerstörungsfreie Prüfverfahren (IZFP) Campus E3.1, 66123 Saarbrücken Outline • Principle of Atomic Force Acoustic Microscopy (AFAM), dynamic operation mode of an Atomic Force Microscope (AFM) in the ultrasonic frequency range • Mechanical models of AFM cantilevers and the contact between a sensor tip and a sample surface, resonance vibrations of the cantilever without and with sample contact • Application of AFAM to image microstructural features and local stiffnesses of α and β phases in the Titanium alloy Ti-6Al-4V Frequencies and Wavelengths of Elastic Waves Hypersound Sensors of Commercial Atomic Force Microscopes Small elastic beams: Length: a few 100 µm, width: a few 10 µm, thickness: a few µm, Sensor tip: Radius of a few nm up to of a few 100 nm, Material: Silicon single crystal (cantilever and chip ond piece), Vibration resonances in the ultrasonic frequency range, i.e. usable as a near field ultrasonic probe. Optical microscopy image SEM image Cantilever 10 µm Sensor tip Typical values: 1. Free bending resonance frequency: 10 - 300 kHz Spring constant: ca. 0.1 - 60 N/m Dynamic AFM Operation Modes with Ultrasonic Frequencies - Atomic Force Acoustic Microsopy (AFAM), vertical und lateral, - Ultrasonic piezo-mode, - Ultrasonic Friction Force Microscopy (UFFM) exploit flexural and torsional vibration resonances of AFM cantilevers Imaging of sample surfaces: Spectroscopy: - Amplit