| 摘要 |
PURPOSE:To accomplish microscopic formation of average crystal grain diameter while the degree of orientation of columnar crystals is being enhanced, and to obtain an RE-YM-B alloy having excellent magnetic characteristics by controlling an injection method, the casting temperature, cooling speed and the like. CONSTITUTION:The so-called horizontal casting method, in which molten metal is cast in a mold composed of a horizontally-arranged chill plate 1 and a heating/heat- insulating plate 2, which is almost horizontally arranged above the chill plate 1, is adopted and a cooling operation is conducted from the side of the chill plate. In this case, the alloy molten metal, containing at least a rare-earth element, a transition element and B as essential ingredients, is cast in the mold arranged in almost horizontal state at 1200 to 1700 deg.C using a top pouring method while the molten metal is being heated or heat-insulated from above the mold, and a cooling operation is conducted from the lower side of the mold at the cooling speed of 5 to 30 deg.C per minute while the temperature gradient in vertical direction of 5 to 30 deg.C per minute or higher is being maintained. Accordingly, columnar crystals grows only upward in vertical direction from the upper surface of the plate 1, the columnar crystal extending in parallel and vertical with each other are formed, and the crystal structure having an excellent degree of orientation can be obtained. |
