Extruded Rods with Axial Texture of Polycrystalline Ni-Mn-Ga Alloys

The Ni-Mn-Ga alloys extruded at high temperature with a relatively large reduction rate were the subject of the studies. The microscopic observations of the transient zone in the extruded rods revealed rotation of the columnar grains in the ingot along the rod axis - giving the preferred orientations. Comparison of the texture, magnetization and magneto-crystalline anisotropy constant for samples cut out from the columnar grain zone and these cut from the extruded rods was carried out for two alloys which differ in chemical composition and Ms temperature. Both alloys have the 5M martensitic structure at room temperature. The samples cut out of the ingot and the extruded rods have shown the axial orientation, similar magnetization curves and magnetocrystalline anisotropy constant Ku = 1.5-1.6 J/m3•105.