Co過剰Co-Fe合金急冷薄帯における磁気特性に及ぼす熱処理効果

摘要

磁歪材料(Magnetostrictive Material)は，磁場を印加して磁化させたときに歪み（磁歪）を生じ，また逆に応力•歪みにより磁化を変化(逆磁歪)させることが可能な材料である.可逆的に電気エネルギーを機械エネルギーに変換する，検知(センサ)と駆動（ァクチユエータ）の両方の機構を持ち，駆動電源を必要としない.そのため，近年のエネルギーの需要と供給，温暖化ガスの排出などの問題から，エネルギーハーべスト（環境中のエネルギーを無駄にせず利用する技術）においても期待されている.また磁歪材料の機能性を生かした技術として逆磁歪式トルクセンサや圧電素子，ならびに複合した圧電磁歪複合センサ，さらには振動発電がある.%In this study, heat treatment effect on the rapidly solidified Co-Fe alloys with high Co content was investigated for synthesizing a compact magnetic sensor with high-performance. The Co-Fe alloy ribbons with 71 and 75 at% Co and with 70 nm in the thickness were produced by a single Cu-roller rapid solidification, and subsequently heat treatment was conducted. For evaluation of the heat treatment effect, magnetic properties such as magnetization, coercivity, magnetostriction and susceptibility were measured as well as crystal structure. The saturation magnetization and saturation magnetostriction for the Co_(71)Fe_(29) ribbon annealed at 750℃ exhibited no remarkable change without any relation to the annealing time. On the other hand the Co_(75)Fe_(25) alloy ribbon revealed annealing time dependency of both magnetization and magnetostriction, it was found that the short time annealing is effective in increasing the saturation magnetostriction. Maximal saturation magnetostriction of the Co_(75)Fe_(25) alloy ribbon annealed at 750℃ reached to 96 ppm, 33% higher than that of the Co_(71)Fe_(29) alloy. As a result magnetostrictive susceptibility for the annealed Co_(75)Fe_(25) alloy ribbon became higher than that of the annealed Co_(71)Fe_(29) alloy ribbon and it is considered that the optimal annealing Co_(75)Fe_(25) alloy ribbon has excellent functionalities as an element material of the magnetic sensor.