Annealing effect and measurement of magnetostriction in Fe₄₉Co₄₉V₂ alloy using the Michelson laser interferometer

We investigate the annealing effects of microstructure, magnetostriction in Fe₄₉Co₄₉V₂ and soft magnetic properties of B-H hysteresis loops. Fe₄₉Co₄₉V₂ alloy samples are prepared in a thermal annealing furnace at temperatures between 500 and 900°C. A Michelson laser interferometer with a feedback signal of optical path length (OPL) variation is employed for measuring magnetostriction of the samples. As the annealing temperature increases, the grain size related to texture of the alloy samples increases due to recrystallization. After annealing at a high temperature of 900°C, the magnetostriction value increases from 2 × 10^-6 to 33 × 10^-6 at H = 60 Oe. The results suggest that the magnetostrictive characteristics are improved by the microstructural modification.