Temperature dependence of the magnetostriction and magnetoelastic coupling in Fe100−xAlx (x = 14.1,16.6,21.5,26.3) and Fe50Co50

In this paper, we report magnetostriction measurements, (λ100) on Fe-rich Fe–Al alloys and Fe50Co50 as functions of temperature from 77 K to room temperature (RT). From these measurements and elastic constant (c′) measurements, the tetragonal magnetoelastic coupling constants (b1’s) were calculated. Significant differences were found between our RT measurements and earlier magnetostriction measurements for the higher Al concentration alloys (16.6%, 21.5%, 26.3% Al) and the Fe50Co50 alloy. Reminiscent of the temperature dependence of λ100 for pure Fe, magnetostriction changes with temperature are minimal for Fe–Al alloys having the disordered bcc (A2)structure (x\u3c19% Al). In contrast, the alloy possessing the ordered (D03) structure shows an anomalous decrease in magnetostriction in λ100 with decreasing temperature. For the Fe–Al alloy system, the magnetoelastic coupling constant, ∣b1∣, exhibits a peak at room temperature maximizing at 16.6% Al with a value of 12.3 MJ/m3. For Fe50Co50, ∣b1∣ was calculated to be ∼ 34 MJ/m3 at room temperature