Self-excited oscillation and non-linear anelasticity of In20 at.% Tl due to transformation twins

Non-linear anelasticity of In20 at.% Tl thermoelastic martensite is studied by measuring self-excited oscillations and resonance curves. The self-excited frequency is of the order of one-tenth of the driving frequency, and thus the fundamental wave is amplitude-modulated by the self-excited oscillation. The modulation frequency depends on temperature and shows a maximum near 5°C. The activation energies estimated are roughly half of the activation energy for impurity diffusion of Tl in In. The experimental results obtained are similar to those of In-19.1 at.% Tl by Wuttig and Lin. The impurity drag effect, as applied to the twin anelasticity in InTl by Wuttig and Lin, and the effects of assumed triangular and rectangular potentials between Tl atom and twin boundary on the temperature dependence of the maximum modulation frequency are discussed.