Ferromagnetic shape memory alloy (FSMA) is recently known as a new type of magnetically driven solid state actuator material, which has large strain as well as a quick response to the mechanism of re-arrangement of martensite twin by magnetic field. In this study, Fe-29.6 at%Pd alloy ribbons formed by rapidly solidified, melt-spinning methods were studied. Samples showed strong anisotropy and large magnetostriction, ε=600∼800×10-6 at nearly perpendicular direction to its plate surface (θ= 90°) at room temperature. The ε vs. temperature, T curve had a maximum at 370∼400 K, then decreased steeply with increasing T. Magnetization, M and applied magnetic field, H loops also showed anisotropic behaviour similar to ε vs. H curve. It was found that the coercive force, Hc= 6.1 kA · m-1, at θ= 90° decreased steeply in the range of 293 to 320 K and then it reached to constant, 2 kA · m-1 with T. Since the remarkably decrease of Hc is caused by the disappearance of the obstacles against magnetization, i.e. martensite twin variants in the lower temperature phase, it is suggested that Af equals to about 320 K. By X-ray diffraction analysis, the Af from fct to fcc is 330 K, which seems to coincide with the result by the Hc vs. T curve. Shape memory effect vs. T curve had two sharp increasing points near 320 K and 400 K which correspond to the phase transformation temperatures estimated by X-ray, Hc and ε, respectively.
|ジャーナル||Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals|
|出版ステータス||Published - 2001|
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