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

在千周和兆周两个频段分别测量了含Cd为46.1at％,47.5at％,50.0at％和52.5at％的AuCd合金中与马氏体转变有关的内耗和杨氏模量。实验结果表明,在千周范围,由于马氏体转变引起的Q^-1(内耗)是静滞后型的。Q^-1峰的形成可以用弹性软化及界面位错的静滞后阻尼机制来解释。而兆周范围的超声衰减是与频率有关的,表明尚有共振型及弛豫型阻尼的成份。此外,实验还观察到AuCd合金的等温马氏体转变Q^-1峰以及预马氏体相变Q^-1峰。 关键词：

INTERNAL FRICTION ASSOCIATED WITH MARTENSITIC AND PREMARTENSITIC PHASE TRANSFORMATION IN THE kHz AND THE MHz RANGE

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.