Internal friction and pseudoanelasticity associated with phase transformation

There exists high damping peak associated with the diffusional pearlitic transformation in Fe-Ni-C, indicating that the motion of interphase, especially the interface with high boundary energy, plays an important role to internal friction. An expression of the relationship between value of internal friction peak and interphase boundary energy is suggested. In Fe-Ni-C, the characteristic of the internal friction associated with the pearlite transformation is similar to that of the bainite transformation. It has been revealed that the internal friction peak appeared in the incubation period of the isothermal bainite transformation and the experiment also found that the solute-depleted zone formed beyond this period. Combination of the above results just implies that the nucleation mechanism of bainite transformation is diffusional. The lower interphase energy in the martensitic transformation results in a lower value of internal friction peak as compared with that in diffusional transformation. The soft mode phenomenon gives an implication for the nucleation mechanism. Antiferromagnetic transition depresses the kinetics of the martensitic transformation fcc-->hcp, but enhances the fcc-->fct transformation. In ZrO2-CeO2-Y2O3 ceramics, anelasticity phenomenon induced by the reverse transformation m-->t may be called pseudo-anelaticity and the relaxation process will proceed as long as several days.