Magnetostrictive and Shape Memory Properties of Heusler Type Co₂NiGa Alloys

Abstract

We have researched and developed a new Heusler-type ferromagnetic shape memory alloy Co₂NiGa, which has large magnetostriction caused by the magnetic-field-induced re-arrangement of martensite twin. The ribbon samples produced by rapid-solidification melt-spinning method show strong texture and large magnetostriction ε of about 110×10⁻⁶ for an applied magnetic field of 800 kA·m⁻¹ at room temperature. When increasing temperature, the martensite phase of Co_52.4Ni₂₂Ga_25.6 and Co_52.1Ni_26.1Ga_21.8 ribbons disappears at about 390 K and 330 K, respectively, where the drastic shape recovery arises. Some of the ribbons have good ductility and are not broken even after bending to an angle of 180^°, indicating that the Co₂NiGa system has a possibility of new ferromagnetic shape memory material with good ductility.