Influences of Fe-Ga Alloy Crystallinity for the Application to a Magnetostrictive Vibration Energy Harvester

An isotropic poly-crystalline Fe-Ga alloy was fabricated using a short-time process and its performance as a magnetostrictive vibration energy harvester was evaluated. Grain enlargement due to recrystallization was observed by annealing treatment exceeding 1100 °C, but no contribution to physical properties and power generation performance was observed. It was confirmed that the magnetostrictive vibration energy harvester using poly-crystal functioned and an output of 1.1 mW was obtained under the vibration condition of a resonance frequency of 106 Hz and acceleration of 0.8 G. This is an output of 28% compared with the case of using a single crystal. In a trial calculation, poly-crystalline Fe-Ga alloy can be fabricated at a cost of 1/6 of a single crystal, so potential for using poly-crystal is expected in applications not requiring high output. (paper)