D. Kitanosono, T. Ohba, S. Morito, Shimane University, Matsue, Japan; T. Fukuda, M. S. Choi, T. Kakeshita, Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, Suita, Osaka, Japan; S. Tsutsui, A. Baron, SPring-8/JASRI, Sayo, Japan
Ti-Ni alloy system is one of typical alloy systems showing martensitic transformation and has been used for the study of the transformation mechanism. Recently, Choi et al. reported electric resistivity(ρ), magnetic susceptibility(χ) and specific heat (Cp) measurements in Ti50Ni50-xFex (x=2,4,6,8,10,20at%.) alloy (Hereafter we denote the alloy by their Fe content. For example the 2Fe alloy represents the Ti50Ni48Fe2). They reported that temperature dependent of ρ, χ and Cp in 2Fe and 4Fe indicated first-order transformation, corresponding to R-phase transformation. Temperature dependent of ρ, χ and Cp in 6Fe and 8Fe indicated second-order like transformation. Furthermore, they performed electron diffraction experiments and reported that incommensurate reflections in 6Fe shifted to commensurate positions approaching martensitic transformation temperature, 180K. The commensurate reflections correspond to R-phase. On the other hand, incommensurate reflection in 8Fe didn't shift to commensurate positions, even at 121K. In 1980’s, Moine et al. and Satija et al. performed inelastic neutron scattering experiments and measured [ζζ0]TA2 phonon with 3Fe and 3.2Fe, and reported phonon softening around ζ=1/3. Satija et al. indicated that the linewidth of inelastic peak above ζ>0.3 were too broad to determine the peak position. In the present study, we performed inelastic X-ray scattering (IXS) experiments for observing [ζζ0]TA2 phonon in Ti50Ni44Fe6 and Ti50Ni42Fe8. Synchrotron facility, BL35XU at SPring-8 was utilized for IXS experiments. Inelastic peaks were observed, and shifted to zero with cooling corresponding to phonon softening.
Summary: Recently, Choi et al. reported electric resistivity, magnetic susceptibility and specific heat measurements in Ti50Ni50-xFex (x=2,4,6,8,10,20at%) alloy.Temperature dependent of electric resistivity, magnetic susceptibility and specific heat in 6Fe and 8Fe indicated second-order like transformation.
In the present study, we performed inelastic X-ray scattering (IXS) experiments for observing [zz0]TA2 phonon in Ti50Ni44Fe6 and Ti50Ni42Fe8. Synchrotron facility, BL35XU at SPring-8 was utilized for IXS experiments. Inelastic peaks were observed, and shifted to zero with cooling corresponding to phonon softening.
