Magnetic and structural transformation in off-stoichiometric NiMnGa alloys

The effect of Mn/Ga ratio on crystal structure, phase transformation, microstructure and magnetic properties has been investigated in Ni50Mn30+xGa20−x ferromagnetic shape memory alloys. The solidification microstructures of the as-cast alloys display either equiaxed or dendritic morphology with latter more pronounced in Mn-rich alloys. The martensitic transformation and the magnetic properties of the alloys are found to depend strongly on Mn/Ga ratio and thermal processing of the alloys.