Date | Time
19/12/2013 | All Day
« Microstructure, martensitic transformation and magnetocaloric effect in polycrystalline Ni-Mn-Ga alloys »
Dr Zongbin LI
Abstract As a novel type of multi-functional smart materials for potential uses in sensor and actuator devices, Ni-Mn-Ga alloys have attracted considerable attention due to their large output and quick response under magnetic field. These alloys also demonstrate large change in magnetic entropy under the magnetic field at the vicinity of the magneto-structural transformation and thus a giant magnetocaloric effect, which could be potentially exploited for magnetic refrigeration applications. In this work, based on the spatially resolved electron backscatter diffraction (EBSD) technique, the microstructural features of three types of martensite and the martensitic transformation crystallography in polycrystalline Ni-Mn-Ga alloys were studied in detail. Furthermore, possible routes for the texturation of polycrystalline alloys via external field treatment were explored, and the composition dependent magnetocaloric effect of melt-spun ribbons and the property improvement through microstructure control were demonstrated.