Phase Transformation and Magnetic Property of Heusler Type Co₂NiGa Alloys

Abstract

We studied the phase transformation of a new Heusler type ferromagnetic shape memory alloy, Co₂NiGa, by using an Acoustic Elastometer method. The alloy displays large magnetostriction, caused by the magnetic-field-induced rearrangement of martensite twin boundary. The ribbon samples produced by rapidly solidified melt-spinning method show large magnetostriction of about 100 × 10⁻⁶ at room temperature. While heating and cooling, the modulus defect, ΔM/M, and damping, Q⁻¹, of the ribbon sample exhibits drastic changes at A_s and M_f, which differ slightly from the magnetic results.