A single crystal of Cu74.08Al23.13Be2.79 undergoes a martensitic phase transition at 246 and 232K under heating and cooling, respectively. The phase fronts between the austenite and martensite regions of the sample were weakly mobile with a power-law resonance under external stress fields. Surprisingly, the martensite phase was elastically much harder than the austenite phase showing that interfaces between various crystallographic variants were strongly pinned and cannot be moved by external stress while the phase boundary between the austenite and martensite regions in the sample remains mobile. This unusual behavior was studied by dynamic mechanical analysis and resonant ultrasound spectroscopy. The remnant strain, storage modulus, and internal friction were recorded simultaneously for different applied forces in dynamic mechanical analysis. With increasing forces, the remnant strain increases monotonously while the internal friction peak height shows a minimum at 300 mN. Transmission electron microscopy shows that the pinning was generated by dislocations which were inherited from the austenite phase

Mechanical Resonance of the Austenite/Martensite Interface and the Pinning of the Martensitic Microstructures by Dislocations in Cu74.08Al23.13Be2.79. E.K.H.Salje, H.Zhang, H.Idrissi, D.Schryvers, M.A.Carpenter, X.Moya, A.Planes: Physical Review B, 2009, 80[13], 134114