Temperature-Induced Phase Transitions of Fe-Ga Alloys for Sensors

Slow cooled arc melted Fe-Ga alloys with different compositions were characterized. GI-XRD confirms the BCC structure and existence of single phase A2 in 17 at.% of Ga and multiphase A2 and L1 2 in 30 at. % of Ga. The Ga defects migrates during annealing and reduces the lattice. The Galfenol alloy with the 30 at.% of Ga has an A2 phase around 400 o C and an L1 2 phase around 560 o C. The formation of the L1 2 structure is due to an exposure in high temperature region. The magnetostriction of Fe 83 - Ga 17 and Fe 70 - Ga 30 alloys seems to be 64 and 27 ppm. Decrement of magnetostriction is due to change in anisotropy coefficient.