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MM: Fachverband Metall- und Materialphysik

MM 6: Microstructure and Phase Transformations I - Martensitic phase transformations

MM 6.3: Talk

Monday, March 31, 2014, 10:45–11:00, IFW B

Laser annealing of Fe7Pd3 ferromagnetic shape memory thin films — •Ariyan Arabi-Hashemi¹, Martin Ehrhardt¹, Pierre Lorenz¹, Dietmar Hirsch¹, Klaus Zimmer¹, and Stefan G. Mayr^1,2,3 — ¹Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstraße 15, 04318 Leipzig, Germany — ²Translationszentrum für regenerative Medizin, Universität Leipzig, 04103 Leipzig, Germany — ³Fakultät für Physik und Geowissenschaften, Universität Leipzig, 04103 Leipzig, Germany

Fe7Pd3 is a magnetic shape memory alloy capable of performing strains of up to 5% by applying an external magnetic field. While the austenite phase of Fe7Pd3 is fcc, the martensite phases are fct, bct and bcc. The magnetic shape memory effect is only observed in the fct phase due to a high magnetocrystalline anisotropy and a high mobility of twin boundaries. We study phase transformation effects in Fe7Pd3 films annealed by 25 ns pulses of a KrF laser for various substrates: LaSrAlTaO, MgO and Si. The laser-solid interaction was simulated by finite element method. Laser annealing experiments are compared with thermal annealing experiments. Low temperature electron beam evaporation deposited samples reside in the bcc phase independently of the used substrate. Subsequent laser and thermal annealing of Fe7Pd3 films deposited on MgO reside in the bcc phase, while laser annealed Fe7Pd3 films on LSAT show a phase transformation from bcc to fcc. In thermally annealed Fe7Pd3 on LSAT fcc and fct is observed. Interdiffusion was studied by SIMS.