Regensburg 2013 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 63: Computational Materials Modelling - Phase Stability IV
MM 63.4: Vortrag
Donnerstag, 14. März 2013, 18:00–18:15, H24
Acoustic emission during the martensitic transformation of a Ni-Mn-Ga single crystal under compressive stress — •Robert Niemann1,2, Jordi Baró3, Oleg Heczko4, Ludwig Schultz1,2, Sebastian Fähler1,2, Eduard Vives3, Lluis Mañosa3, and Antoni Planes3 — 1IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany — 2Department of Physics, Institute for Solid State Physics, Dresden University of Technology, 01062 Dresden, Germany — 3Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona. Diagonal 647, 08028 Barcelona, Catalonia, Spain — 4Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, 182 02 Prague, Czech Republic
The propagation of a phase front during a thermally induced martensitic transition is discontinuous due to pinning at various defects, an effect which results in acoustic emission. Here we analyze the consequences of an applied compressive stress exemplarily on a Ni-Mn-Ga single crystal. Our experiments show that the distribution of the energies of the acoustic emission events follows a power law for more than 3 decades. This indicates that the transition exhibits avalanche criticality. The exponent characterizing the distribution of energies depends on the applied stress and decreases from 1.9 at zero stress to 1.5 at stress above 3 MPa. This decrease could be attributed to the reduced multiplicity of variants possible under uniaxial compression.