Author:

Keywords:

ultrasonics, acoustic properties, elasticity, martensitic phase, dislocations, internal-friction, crystals, transformation, 0204 Condensed Matter Physics, 0912 Materials Engineering, 0914 Resources Engineering and Extractive Metallurgy, Materials

Abstract:

The present work continues the series of experimental investigations undertaken in order to elucidate the mechanisms controlling elastic and anelastic properties of the beta(1)' martensitic phase of Cu-based shape memory alloys. The paper reports an attempt to distinguish between 'dislocation' and 'interface' mechanisms of the internal friction in the beta(1)' martensitic phase of Cu-Al-Ni single crystals. Two types of experiments have been performed. First, the ultrasonic strain amplitude-independent and amplitude-dependent internal friction (ADIF) of a monovariant specimen for temperatures 90-300 K is carefully re-examined. Second, in situ measurements of the ADIF and of the influence of ultrasonic oscillations on the plastic deformation (acoustoplastic effect) were carried out during quasistatic deformation of a quenched polyvariant specimen. Experimental results support a dislocation rather than an interface mechanism of anelasticity, at least at ultrasonic frequencies and moderate strain amplitudes. (C) 2000 Elsevier Science S.A. All rights reserved.