INTERNAL FRICTION AND ELASTIC MODULUS OF AuCd IN THE VICINITY OF MARTENSITIC TRANSFORMATION

Abstract
The internal friction and modulus related to martensitic transformation in 4 kinds of AuCd alloys were measured at low and high frequencies. The heights of the Q^-1 peaks (at 49 KHz and 1 Hz) increased significantly in successive measuring runs, whereas no change was observed in modulus variation. It was associated with the increase of interfaces of parent-martensite by the metallographic examination. The low frequency damping was confirmed as a static hysteresis loss and the formation of the Q^-1 peak was explained in terms of the localized soft mode theory and dislocation damping. The high frequency damping has the component contributed by viscous motion of dislocation. Otherwise, we found a Q^-1 peak during isothermal transition and a broad Q^-1 peak appearing in the temperature range of premartensitic transformation.