Vibrational Behaviour of Cu-Based BCC Alloys

Departament d'Estructura i Constituents de la Matèria, Facultat de Fίsica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Catalonia, Spain

Abstract

Using experimental data from ultrasonic and neutron scattering measurements for different Cu-based bcc alloys undergoing a martensitic transformation, we show that: (i) the relationship between the elastic constant C’ and the zone boundary frequency ω_ZB of the associated phonon branch, both evaluated at the transition point T_M, conforms to the dependence predicted by a Landau model, recently proposed for martensitic transformations and (ii) the elastic anisotropy A at T_M has, within the experimental accuracy, a constant value; this last finding being not explained by the existing models. Some suggestions are envisaged to account for this fact.