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Subsurface imaging of grain microstructure using picosecond ultrasonics
- Source :
- Acta Materialia. 112:209-215
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- We report on imaging subsurface grain microstructure using picosecond ultrasonics. This approach relies on elastic anisotropy of crystalline materials where ultrasonic velocity depends on propagation direction relative to the crystal axes. Picosecond duration ultrasonic pulses are generated and detected using ultrashort light pulses. In materials that are transparent or semitransparent to the probe wavelength, the probe monitors gigahertz frequency Brillouin oscillations. The frequency of these oscillations is related to the ultrasonic velocity and the optical index of refraction. Ultrasonic waves propagating across a grain boundary experience a change in velocity due to a change in crystallographic orientation relative to the ultrasonic propagation direction. This change in velocity is manifested as a change in the Brillouin oscillation frequency. Using the ultrasonic propagation velocity, the depth of the interface can be determined from the location in time of the transition in oscillation frequency. A subsurface image of the grain boundary is obtained by scanning the beam along the surface. We demonstrate this subsurface imaging capability using a polycrystalline UO2 sample. Cross section liftout analysis of the grain boundary using electron microscopy was used to verify our imaging results.
- Subjects :
- 010302 applied physics
Materials science
Polymers and Plastics
business.industry
Metals and Alloys
02 engineering and technology
021001 nanoscience & nanotechnology
01 natural sciences
Refraction
Electronic, Optical and Magnetic Materials
Brillouin zone
Wavelength
Optics
Picosecond
0103 physical sciences
Ceramics and Composites
Picosecond ultrasonics
Ultrasonic sensor
Grain boundary
Crystallite
0210 nano-technology
business
Subjects
Details
- ISSN :
- 13596454
- Volume :
- 112
- Database :
- OpenAIRE
- Journal :
- Acta Materialia
- Accession number :
- edsair.doi...........758e168dfc735c30346e284c3f774fc5