Multi-functional properties of iron-based ferromagnetic shape memory ribbons

This paper presents measured multi-functional properties of Fe–Mn–Cr–Si–Tb–B ribbons developed by means of the melt-spinning technique in air. The alloys are multi-functional materials, which have both ferromagnetic and shape memory properties. If we can simultaneously improve the material properties, the applications of the shape memory alloys will be widened dramatically in the field of the electromagnetic sensors and actuators. The base shape memory material, Fe–Mn–Si alloy, is nonmagnetic due to its high manganese content (28–34 Mn, 4–6.5Si wt%). In order to improve ferromagnetic function of the Fe–Mn–Si alloy, we have investigated the addition of rare earth elements. Addition of about 0.7–1.0 wt% Tb was effective in increasing the saturation magnetization. However, ductility of the samples was not good and it was difficult to evaluate the shape memory properties with shape recovery strain measurements. The detailed magnetic and shape memory properties of the Fe–Mn–Cr–Si–Tb–B alloys are discussed in this paper.