Recent development of the magnetic shape memory materials research in Finland Outi Söderberg 1 , Ilkka Aaltio 1 , Yanling Ge 1 , Alexandr Soroka 1,2 , Raisa Niemi 1 , Xuwen Liu 1 , Simo-Pekka Hannula 1 1 Department of Materials Science and Engineering, Helsinki University of Technology, POB 6200, FI-02015, TKK, Espoo, Finland. 2 AdaptaMat Ltd., Yrityspiha 5, FI-00390, Helsinki, Finland. ABSTRACT Ni-Mn-Ga based magnetic shape memory (MSM) materials have been studied since 1998 in Finland at the Helsinki University of Technology (TKK, previously HUT). The large HUT- MSM-project resulted in MSM-alloys with high service temperature, 10 % field-induced-strain, as well as circumstances when and how a Ni-Mn-Ga alloy exhibits this phenomenon. The understanding of the structure and behavior of twin boundaries, and their role, for example, in the vibration damping and long-term actuation has been enhanced in the recent projects. Twin boundaries have been studied by XRD, by high-resolution transmission electron microscopy (HRTEM), and by in-situ straining in TEM, the last one in co-operation with the Institute of Physics in Prague (ASCR-IP), Czech Republic. The results obtained by neutron diffraction in co- operation with Hahn-Meitner-Institut Berlin, Institute for Metal Physics (IMP), Kiev, and Institut Laue-Langevin (ILL), Grenoble, have given new crystallographic information. Damping of Ni- Mn-Ga polymer composites has been proved to be excellent at high stiffness levels with the loss factor δ = 0.6 at E ≈ 1 GPa. This research was carried out in co-operation with the University of California Los Angeles (UCLA), USA. In the long-term actuation, a fatigue life of 2x10 9 has been recorded for a five-layered modulated Ni-Mn-Ga structure in mechanical cycling. The evolution of the MSM parameters during the long-term use is recorded and used as an input data for the models developed in the European MAFESMA co-operation. The search for alloys with wide stable thermal property range showing MSM effect has continued and alloys that are stable down to 4 K have been established. Modeling based on Ginsburg-Landau theory has been applied to evaluate aging and thermal fluctuations in the modulated Ni-Mn-Ga structures. As a commercial target, AdaptaMat Ltd. develops technology to produce Ni-Mn-Ga magnetic shape memory material with improved quality, lower twinning stress, longer fatigue life as well as lower cost and better availability for use in research and development. INTRODUCTION The basis of the magnetic shape memory, MSM, research in Finland was set in 1995 with the studies of magnetic field induced martensite twin structure orientation in a Fe-Ni-C alloy by Ullakko and Aaltio [1]. This observation was confirmed in a Ni-Mn-Ga alloy at MIT by Ullakko [2]. The earlier material development of the Ni-Mn-Ga alloys in Ukraine provided this material with the preferential structure and anisotropic magnetic properties [3]. AdaptaMat Ltd. was founded in 1996 to serve the industrial purposes of fabricating and applying MSM materials. As the first results of the magnetic-field-induced strain (MFIS) were obtained at too low temperature (265 K) for most practical applications, the multidisciplinary HUT-MSM research project (1998- 2003) was launched simultaneously with the expanding interest in this research field worldwide Mater. Res. Soc. Symp. Proc. Vol. 1200 © 2010 Materials Research Society 1200-G03-03