Magnetostriction of ternary Fe–Ga–X alloys (X=Ni,Mo,Sn,Al)

Abstract

Investigations were made into the effect of small additions of Ni, Mo, Sn, as well as larger additions of Al on the magnetostriction of single crystal Fe100−xGax alloys (x≅13). The Fe–Ga and Fe–Al systems are seemingly unique among the Fe-based alloys in having very large magnetostrictions in spite of Ga and Al being nonmagnetic. In this paper, we show how additions of Ni, Mo, Sn, and Al affect λ100 and λ111 of the binary Fe–Ga alloys. We substituted small amounts of Ni into a binary Fe–Ga alloy in an attempt to reduce the magnitude of the negative λ111, as Ni does in Fe, in order to improve the magnetostriction of polycrystals. The measured λ111’s were reduced to a very small value, ∼3 ppm, but λ100 fell dramatically to +67 ppm for Fe86Ga11Ni3. Mo was substituted for Ga to determine the effect of a partially filled 4d shell on the magnetostriction. Here |λ111| is affected the most, increasing to a value greater than all known α-Fe-based alloys (λ111=−22 ppm for Fe85Ga10.2Mo4.8). We find that the addition of Sn, with its very large atomic radius, makes only small changes in both λ100 and λ111. For Fe86.1Ga12.4Sn1.5 at room temperature, λ100=+161 ppm and for Fe86.7Ga12.0Sn1.3, λ111=−15 ppm. The decrease of λ100 in Fe87(GayAl1−y)13 was approximately linear, going from 67 ppm at y=0 to 154 ppm at y=1.