Noncontact ultrasonic spectroscopy on deforming polycrystalline copper: Dislocation damping and acoustoelasticity
- National Inst. of Standards and Technology, Boulder, CO (United States)
- Osaka Univ., Toyonaka, Osaka (Japan). Graduate School of Engineering Science
Electromagnetic acoustic resonance (EMAR) is developed for the continuous measurement of the bulk-wave attenuation and phase velocities in a metal during a deformation process. The EMAR enables one to perform the noncontact measurement with extremely high sensitivity, in which the electromagnetic acoustic transducer (EMAT) generates and detects the bulk waves without any coupling material. The attenuation and velocity responses to the uniaxial stress were continuously recorded for 99.99 wt pct pure polycrystalline copper annealed at 200 C for 1 hour before loading. The authors separated the velocity change due to the acoustoelastic effect from the contribution of the dislocation movement responding to the ultrasonic waves, and determined the pure third-order elastic constants. The shear wave showed much larger sensitivity to the dislocation mobility than the longitudinal wave. The discontinuous change in the incremental rate of the shear wave attenuation was observed in the elastic region, which was interpreted as the onset of the microscopic yielding.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 316033
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 29, Issue 12; Other Information: PBD: Dec 1998
- Country of Publication:
- United States
- Language:
- English
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