INTERNAL FRICTION ASSOCIATED WITH MARTENSITIC AND PREMARTENSITIC PHASE TRANSFORMATION IN THE kHz AND THE MHz RANGE
千周和兆周范围的马氏体相变内耗以及预马氏体相变内耗

The internal friction (49kHz), ultrasonic attenuation (4-82 MHz) and Young's modulus associated with martensitic transition (MT) were measured in AuCd alloys containing 46.1 at%, 47.5 at% and 52.5 at% Cd respectively.The internal friction due to MT in the kHz range was confirmed as the hysteresis loss just the same as we have disclosed in the Hz range. The origin of internal friction peak was explained by elastic softening and the interaction of the interface dislocations with point defects. But the ultrasonic attenuation in the MHz range is frequency dependent, this implies that there exist components of resonance and relaxation loss contributed by viscous motion of dislocations.In addition, the isothermal martensitic transition peak and the premartensitic phase transformation peak in AuCd alloys were observed as well.