Anomalous phonon behavior in the high-temperature shape-memory alloy Ti50Pd50-xCrx

TitleAnomalous phonon behavior in the high-temperature shape-memory alloy Ti50Pd50-xCrx
Publication TypeJournal Article
Year of Publication2007
AuthorsShapiro SM, Xu GY, Winn BL, Schlagel DL, Lograsso T, Erwin R
Journal TitlePhysical Review B
Date PublishedAug
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000249155100067
Keywordselectron-microscopy, phase, premartensitic phenomena, TI50PD42CR8, TRANSFORMATION

Ti50Pd50-xCrx is a high-temperature shape-memory alloy with a martensitic transformation temperature strongly dependent on the Cr composition. Prior to the transformation, a premartensitic phase is present with an incommensurate modulated cubic lattice with wave vector of q(0)=(0.22,0.22,0). The temperature dependence of the diffuse scattering in the cubic phase is measured as a function temperature for x=6.5, 8.5, and 10 at. %. The lattice dynamics has been studied and reveals anomalous temperature and q dependences of the [110]-TA(2) transverse phonon branch. The phonon linewidth is broad over the entire Brillouin zone and increases with decreasing temperature, contrary to the behavior expected for anharmonicity. No anomaly is observed at q(0). The results are compared with first principles calculation of the phonon structure.

Alternate JournalPhys. Rev. B