Inversion of acoustic emission asymmetry accompanying martensitic transformations in titanium nickelide alloys

Asymmetry of the acoustic emission indicates that the processes of nonchemical energy scattering differ in the direct and reverse martensitic transformations. An analysis of the inversion of the emission asymmetry with increasing nickel concentration in binary Ti-Ni alloys and in the course of multiple transformation cycles suggests that in a direct transformation nonchemical energy is dissipated by plastic relaxation whereas in a reverse transformation it is dissipated by dynamic relaxation. Significantly plastic relaxation degrades to saturation and dynamic relaxation begins to appear exclusively. (C) 1999 American Institute of Physics. [S1063-7850(99)02312-5].