Ikerbasque Research Professor, BCMaterials & University of Basque Country, Spain

Prof. Volodymyr A. Chernenko graduated Moscow State University in 1975. He has got his PhD degree in Chemical Physics from the same University in 1980. He has 38 years of research experience in centres in Ukraine, Germany, Japan, Italy, United States, France, Switzerland, Australia, Spain, Hong Kong and Russia. He is holding a permanent position as Ikerbasque Research Professor at BCMaterials & University of Basque Country. Professional interest is in physics of phase transitions in solids, magnetism, high pressure physics, functional materials, metallurgy and, in particular, focused on research and development of the multifunctional magnetic shape memory materials, magnetomechanics of martensites, thin films and nanotechnologies of the ferromagnetic martensites.

He is author and co-author of 315 original papers in ISI scientific journals and book chapters with more than 6500 citations and h-index equal to 39. He is author of 14 patents. He is International Fellow Awardee of the Helmholtz Association (Germany) in 2014. He is world-wide known as one of the founders of the new research area “Ferromagnetic shape memory alloys” being organizer and/or invited speaker of many International conferences and symposia on this subject.

Speech Title: Ni-Mn-Ga/Polymer Smart Composites

Aims: Heusler-type NiMnGa is a prototype of Ferromagnetic Shape Memory Alloys (FSMAs) exhibiting, in a bulk single crystalline form, a giant magnetic field induced strain (MFIS) due to martensitic twins rearrangements. General objective of the present work was to elaborate a production technology of the magnetostrain active NiMnGa particles/polymer composites, representing a new smart material for actuation and sensing.

Methods: Fabrication of magnetostrain active NiMnGa particles consisted of careful disintegration of the NiMnGa polycrystalline alloy into separated grains; placing particles into special silicone polymer matrix and curing it under magnetic field. MFIS of a whole composite and individual particles inside it were measured optically with a CCD camera and by X-ray micro-computed tomography (CT) set up, respectively. Stress-strain behavior was also studied.

Results: The first of its kind result obtained is two-fold: (a) the composite in the field of about 0.7T, applied perpendicularly to the sample texture, exhibited a large shape change: 4.0% in the elongation and -2.0% in the contraction; and (b) this MFIS was fully recoverable after removal of the magnetic field. It was disclosed experimentally and theoretically that the effect (a) is produced by the cooperative magnetic field induced shape change of particles (due to twin boundaries motion), whereas the effect (b) is a result of the reverse local stresses in polymer accumulated near close-neighboring particles during field application and local stresses relaxation during field removal.

Conclusions: The utilization of the elaborated composite material exhibiting a magnetic field-induced rubber-like effect can significantly simplify the actuation or sensing devices since no external biasing force is required to reset it after removal of the magnetic field. The magnetostrain active composite and its unusual properties suggest novel solutions for the development of the low cost magnetic actuators and sensors for haptic applications.