Using the Acoustic Coupling Technique (ACT) developed by G. Gremaud, several interactions mechanisms have been experimentally observed and theoretically described, leading for instance to the description of a « phase diagram » of the complex interaction mechanisms taking place between dislocations and more or less mobile point obstacles in FCC metals (Ø. Bremnes PhD thesis n. 2277, 2000). In collaboration with A. Kustov (Universitat de les Illes Balears, Palma de Mallorca, Spain), we studied the long range elastic interaction between dislocations and point obstacles in solid solutions, using the PUCOT technique (Piezoelectric Ultrasonic Composite Oscillator Technique). We developed a model in order to explain the observed athermal behaviours, by introducing a brownian picture of the dislocation motion, which furnished a complete and well accepted explanation to a very old unsolved problem of the anelastic and plastic behaviours of solid solutions. With A. Kustov, we are also currently studying the collective motion of dislocation dipoles in martensitic materials, which leads to a behavior very similar to vortexes in HT superconductors.
S. Golyandin, S. Kustov, S. Nikanorov, K. Sapozhnikov, A. Sinani, J. Van Humbeeck, R. Schaller and R. De Batist, “Transformation temperatures, elastic and anelastic properties of Cu-Al-Ni crystals subjected to impact loading.”, J. Phys. IV, 11 , Pr8-173-178, (2001).
G. Gremaud, “Dislocation-point defects interactions”, In “Mechanical Spectroscopy, with Applications to Materials Science”, chapter 3.3, Materials Science Forum, vol. 366-368, Trans Tech Publications, Switzerland (2001) , p. 178-247
G. Gremaud, S. Kustov, O. Bremnes, “Ultrasonic techniques: PUCOT and ACT”, In “Mechanical Spectroscopy, with Applications to Materials Science”, chapter 9.2, Materials Science Forum, vol. 366-368, Trans Tech Publications, Switzerland (2001) , p. 652-667
Ø. Bremnes, E. Carreño-Morelli, G. Gremaud, “Influence of the interaction between dislocations and mobile point-defects on the damping spectrum of aluminium”, Journal of Alloys and Compounds, 310, 1-2, 62-67 (2000).
Y. Emel’yanov, S. Golyandin, S. Kustov, S. Nikanorov, G. Pugachev, K. Sapozhnikov, A. Sinani, J. Van Humbeeck, R. Schaller and R. De Batist, “Detection of shock-wave-induced internal stresses in Cu-Al-Ni shape memory alloy by means of acoustic technique.”, Scripta mater. 43 , 1051-1057, (2000).