METHOD FOR MANUFACTURING RARE-EARTHS-BASED ALLOY WITH ULTRALOW OXYGEN CONTENT AND FINE AND HOMOGENEOUS CRYSTALLINE STRUCTURE, BY REDUCTION OF RARE-EARTH OXIDE

摘要

PROBLEM TO BE SOLVED: To manufacture a rare-earths-based alloy of an objective composition, having little content of impurity like oxygen in as-cast condition, a fine and homogeneous crystalline structure, and desired characteristics, while using rare-earth oxides as inexpensive raw materials and recycling expensive rare-earth metal resources. SOLUTION: This method for manufacturing the rare-earths-based alloy by arranging a crucible equipped with a heating device and a rapid cooling solidification means for molten alloy in a sealed chamber, and producing a rapidly cooled and solidified alloy through bringing a molten alloy in the crucible into contact with a rapid cooling solidification means in the sealed chamber of a vacuum or inert gas atmosphere. The method comprises a first step for charging a mixture of a rare-earth oxide powder, a raw material powder consisting of other alloy content powders, and a reducing agent consisting of calcium or hydrogenated calcium powder, into the crucible, a second step for reducing calcium by heating the mixture up to a predetermined temperature in the range between a melting point of calcium (843 deg.C) and 1200 deg.C or lower, a third step for forming a molten alloy and slag by rapidly heating it to a predetermined temperature higher than 1200 deg.C, and a fourth step for rapidly solidifying the molten alloy by bringing the alloy into contact with a cooling roller or disc, while making the alloy flow out of the crucible along with separating it from the slag, after the alloy has reached a predetermined temperature.