Magnetostriction of Fe-X (X = Al, Ga, Si, Ge) Intermetallic Alloys

The dependence of the room temperature magnetostriction on substituting Fe by different X elements (X = Al, Ga, Si, Ge) is discussed. All Fe-X alloys exhibit at the Fe-rich side a similar phase diagram where first a disordered A2 and then an ordered B2 and/or DO3 structure is formed. The magnetostriction lambda(100) increases with increasing substitution exhibiting a first maximum close to 20 at. % for Ga and Al, 10 at. % for Ge, and 5 at. % for Si. The reported magnetostriction behavior of Fe-Ga is similar to that of Fe-Al alloys, while the magnetostriction behavior of Fe-Ge is similar to that Fe-Si alloys. However, for all these alloys, the increase of magnetostriction is observed in disordered A2 structure. In the first case, the magnetostriction behavior can be correlated with the lattice constant, which can be taken as a hint that the substitution of larger X-ions causes a local distortion-as was shown for Fe-Ga by an electron spectroscopy for chemical analysis (ESCA) analysis. The higher this local distortion is, the larger is the enhancement of lambda(100). Additionally, the magnetostriction behavior is influenced also by electronic and structural configurations.