Phase transformations and magnetostriction in Fe100-xGax bulk alloys

Fe-Ga alloys, containing 18, 21, and 23 at.% of Ga, were prepared in bulk form. In their as-cast state, they display a small magnetostriction, that is strongly improved after annealing at 1000 ? for 24 h, and subsequent rapid cooling. Multiple characterization techniques, such as x-ray diffraction, differential scanning calorimetry, Mossbauer spectroscopy, temperature-dependent magnetization curves, hysteresis loops, magnetic force microscopy, and magnetostriction measurements, were exploited in synergy to gain a deep understanding of the structure-property relationships in the studied alloys, before and after annealing. The A2 phase, which is favored in the lower range of compositions and is promoted at the expense of the D 0 3 one by annealing, is responsible for characteristic dendritic and maze magnetic domains, and for the strong improvement of the magnetostriction, which almost reaches 240 ppm (transverse configuration) in the alloys with 18 at.% of Ga, after annealing. Published under an exclusive license by AIP Publishing.

Automated summary

Through the synergy of multiple characterization techniques, a deep understanding of the structure-property relationships in Fe-Ga alloys before and after annealing has been achieved. It was found that the D03 phase is gradually replaced by the A2 phase during annealing, and the A2 phase is responsible for the characteristic magnetic structure and significant improvement in magnetostriction performance.