Vibrating-reed measurements, combined with density functional theory-based calculations, were used to assess the elastic and damping properties of Fe–Pd ferromagnetic shape memory alloy splats. While the austenite–martensite phase transformation was generally accompanied by lattice softening, a severe modulus defect and elevated damping behavior were characteristic of the martensitic state. The latter was interpreted in terms of twin boundary motion between pinning defects via partial so-called twinning dislocations. Energy dissipation was governed by twin boundary drag, primarily due to lattice imperfections, as concluded from the temperature dependence of damping and related activation enthalpies.

Mechanical Properties and Twin Boundary Drag in Fe-Pd Ferromagnetic Shape Memory Foils - Experiments and ab initio Modelling. I.Claussen, S.G.Mayr: New Journal of Physics, 2011, 13[6], 063034