Magnetic and thermal expansion properties in hydrided Fe–Zr amorphous alloys

Abstract

The effect of hydrogenation on the Invar-like thermal expansion anomaly for Fe–Zr amorphous alloys has been investigated. Low temperature magnetization hysteresis has also been examined for the hydrided alloys. The Invar anomaly is changed slightly by hydrogenation only through the increase in the saturation magnetization at 0 K (Mso), since the spontaneous-volume-magnetostriction (ωm) for the anomaly increases in proportion to the square of the saturation magnetization (Ms)2. But, the coupling constant between ωm and M2s is not changed by hydrogenation. Field cooling down to 4.2 K makes the magnetization hysteresis asymmetric in the case of the nonhydrided alloys, while no longer any asymmetrical loop has been observed in the hydrided alloys. Thus, the observed large ωm is explained by the simple ferromagnetic effect, rather than by the concept based on a magnetically mixed state.