| Magnetic property in Alnico V type permanent magnet is improved by adding special elemets, heat treatment in magnetic field and producing columnar structres. This experiment is a part of an investigation into methods of producing columnar structure in Fe-Ni-Al alloy of high Co content, with consequent improvement in their magnetic properties. Alnico V type alloys are coarse grained and columnar growth is readily induced by casting into suitably chilled molds. As increasing amounts of Ti are added to this type of alloy, the grain size becomes progressively smaller, and the production of columnar castings more difficult. Consequently, high coercivity alloys with the composition 14.5% Ni, 28∼35% Co, 4.5% Cu, 7% Al and 5% Ti are extremly fine grained and, when chill cast, form only very small columnar crystals near the chilled face. The occurrence of fine equi-axed crystals in Fe-Ni-Co-Cu-Al-Ti alloys is a function of Al and Ti contents and not Ti contents alone. |
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