Published: Jan 1997
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The results of magnetic and structural investigations of binary and complex alloyed iron-chromium (Fe-Cr)-based high-damping alloys (HDA) have been generalized on the basis of recent data obtained with the authors' participation. Alloys have been tested in the high damping state as well as in the state with a strongly suppressed intrinsic damping capacity. An internal friction method, different mechanical tests, transmission electron microscopy, X-ray scattering, diffraction and refraction of neutrons in the range of small angles, magnetic hysteresis loops, and magnetostriction investigations have all been used. The combination of the last three methods allows us to reveal information concerning magnetic domain structure in the bulk samples. Relaxation and hysteresis internal friction effects in applied magnetic fields allow us to obtain information about interstitial redistributions and dislocation mobility. The increase of annealing temperature of cold-worked alloys leads to the nonmonotonic increase of damping capacity due to magnetomechanical damping (MMD). Simultaneously, a strong structural modification as well as modifications of the magnetic domain structure take place. For a reasonable interpretation of the high intrinsic damping capacity, both aforementioned structures have to be considered.
The magnetic domain structure of Fe-Cr HDAs fundamentally differs in the high damping state and after heat treatment which decreases damping capacity. A good correlation between average magnetic domain size in the bulk of material (obtained by the neutron refraction method) and the specific damping capacity (Ψ) has been obtained. This correlation represents a maximum for Ψ in the average domain size of about 8 μm for different binary and additionally alloyed Fe-Cr alloys. This domain structure may be realized for various alloys with the help of different heat treatments. Therefore the damping capacity of Fe-Cr-based alloys fundamentally depends on the type and parameters of the magnetic domain structure and its interaction with crystalline lattice imperfections in an applied stress.
high damping Fe-Cr alloys, internal friction, X-ray scattering, electron microscopy, neutron refraction, magnetic domain structure, structure detects, domain wall pinning
Scientific researcher, Institute of Physical Metallurgy, Moscow,
Assistant professor, Russian State Aviation Technology University, Moscow,