Mechanical and magnetic investigations of Fe71Ga29 alloys under different thermal treatment temperature and time effects

The mechanical and magnetic properties of magnetostrictive materials are susceptible to high temperature. However, the failure mechanisms and magnetism-related deterioration remain elusive. In this study, the Fe71Ga29 alloys subjected to 0 h, 2 h, 10 h and 32 h-thermal treatment under 573 K were comparatively investigated to quantitatively evaluate the contributions of thermal-treatment time. The hardness fist increases to a maximum value (4.327 GPa) and then decreases with rising temperature. Different from as-cast sample, the thermal-treatment samples show Fe–O structure. The formation of Fe–O give rise to a distinctive variational tendency of coercivity, namely, the coercivity fist decreases and then increases with rising temperature. Another series of as-cast samples were subjected to thermal treatment at 393 K, 418 K, 443 K and 468 K for 2 h, which were performed to analyze the contributions of thermal-treatment temperature. Especially, the hardness was enhanced monotonically and magnetic properties were weakened monotonically with extending the time of thermal treatment.