日本金属学会誌

J. Japan Inst. Metals, Vol. 69, No. 8 (2005),
pp. 649-653

Uniaxial Magnetocrystalline Anisotropy Constant and Twinning Stress of Fe-31.2 mol%Pd Ferromagnetic Shape Memory Alloy

Tatsuaki Sakamoto, Takashi Fukuda and Tomoyuki Kakeshita

Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, Suita 565-0871

Abstract:

We have investigated the uniaxial magnetocrystalline anisotropy constant Ku and the stress required for the rearrangement of martensite variants τreq in a disordered Fe-31.2 mol%Pd ferromagnetic shape memory alloy. The value of |Ku| is obtained from the area enclosed by two magnetization curves (along the easy and hard axes) to be 180 kJ/m3 at 77 K and 80 kJ/m3 at 200 K. The maximum of magnetic shear stress τ magm acting across the twinning plane under the [001]P field is evaluated as the magnetocrystalline anisotropy constant |Ku| divided by the twinning shear s; it is 1.5 MPa at 77 K and 1.6 MPa at 200 K. The value of τ req is evaluated by tensile tests to be about 0.9 MPa at 80 K and about 0.6 MPa at 200 K. Comparing τ magm and τ req, we can quantitatively explain the reason for the rearrangement of martensite variants by magnetic field in this alloy.


(Received 2005/2/24)

Keywords:

ferromagnetic shape memory alloy, iron-palladium alloy, magnetic field-induced strain, rearrangement of variant, magnetocrystalline anisotropy, stress-strain curve


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