Comparison on the ΔE effect in Fe87Ga13 alloy by doping Dy and Tb

Abstract R-doping effects on the magneto-mechanical properties, including Young’s modulus (E) at magnetic field (H), that is ΔE effect, and magnetostriction (λ), of Fe86.8Ga13R0.2 alloys (R = Tb and Dy) are studied. ΔEs/E0 of Fe87Ga13 alloy is 6%, and it is significantly enhanced to 12% by doping Dy, but reduced to 4.5% for Tb-doped alloy. The trend of magnetostriction sensitivity (dλ/dH) of Fe86.8Ga13R0.2 alloys with R is similar to that of ΔEs/E0 with R. Most importantly, strong ΔE effect due to high dλ/dH for Fe86.8Ga13Dy0.2 alloy favors magnetic applications. Large ΔE effect is considered to correlate to magnetic softening and lattice softening by doping Dy. For Tb-doped alloy, the increase of λs might be related to the decrease of Fe content in the matrix due to the appearance of minor Tb2Fe17 phase. However, the decrease of dλ/dH might result from increased coercivity and decreased permeability related to the introduction of Tb2Fe17 phase and result in reduced ΔE effect. The findings of this work provide an effective pathway of enhancing the magneto-mechanical properties for Fe-rich Galfenol alloys.