Using ultrasonics, TiNi's acoustic characteristics are observed in order to fully understand its memory effects. Longitudinal and transverse wave velocities, eight kinds of elastic parameters, and dilational and shear internal frictions are simultaneously measured as functions of temperature in cooling and heating runs between 223 and 374 K in TiNi alloy, using an ultrasonic pulse method. An abrupt decrease from around 300 K in Young and shear moduli, Debye temperatures and internal friction peaks during a cooling run shows a premartensitic TiNi-(II)/TiNi(III) transformation by electron-phonon coupling, accompanied by higher elasticity. A rapid decrease from around 250 K is observed in all four elastic moduli (Young, shear and bulk moduli, and Lame parameter) and Debye temperature and internal friction peaks indicate a TiNi (III)/disordered complex TiNi martensitic transformation due to a volume-nonpreserving deformation.
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2002 Jun 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics