The invention relates to a process for increasing magnetic-fieldinduced strain taking place in polycrystalline Ni2MnGa by means of magnetic heat treatment, comprising (a) producing Ni2MnGa alloy containing Ni in an amount of 50.3-53.0 at % and having a nonstoichiometric composition, (b) raw material of high purity Ni, Mn and Ga are arc melted under argon atmosphere to make polycrystalline ingot, (c) homogenising annealing is carried out on the ingot, (d) after annealing, the ingot is magnetic heat treated by applying magnetic field with magnetic field strength H ≅ 0.7T at 340-350K or 360-460K, followed by air-cooling in magnetic field or quenching in water. After magnetic heat treatment, magnetic-field-induced strain taking place in polycrystalline Ni2MnGa increases by 17%.
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