Phase equilibria and martensitic and magnetic transitions of the β (B2 and L21) phase in the Ni-Fe-Ga system were investigated. The b phase was found to be in equilibrium with the γ (A1 structure) or γ′ (L12 structure) phase. The Curie temperature, Tc, equilibrium temperature, To = (Ms + Af)/2, martensitic transition starting temperature, Ms, and reverse transition finishing temperature, Af, of the β single-phase alloys were sensitive to the Fe and Ga compositions. The Fe substitution for Ni decreased and increased the To and Tc, respectively. The Ga substitution for Ni or Fe decreased both the To and Tc. The entropy change accompanying the reverse martensitic transition showed compositional dependence due to the magnetic contribution. The saturation magnetization Is of the Ni-Fe-Ga system showed a strong dependence on the magnetic valence ZM. The Is values of the Ni-Fe-Ga alloys annealed at 1023 K showed the same Zm dependence as other ferromagnetic shape memory alloy (FSMA) systems.
|ジャーナル||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|出版ステータス||Published - 2007 4月|
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