Low-temperature phase transition of nanoscale copper precipitates in Fe-Cu alloys

The low-temperature internal friction spectra and specific-heat measurements of Fe-1%Cu alloys show the existence of a discontinuity at 122 K which is assigned to the structural phase transition of nanosize-Cu precipitates. The change in the internal friction coefficient across the phase transition, and the enthalpy change are found to be proportional to the precipitate average radius R, showing a linear dependence in the case of internal friction and a R3 dependence in the case of specific-heat anomalies in a very good agreement with theoretical model