Patent ID: 6051047
Filing Date: 2000-04-18
Classification: B22F,C22C,H01F

Abstract:
A process for the preparation of Nd--Fe--B permanent magnetic alloys, comprising the steps of:(a) mixing an aqueous solution of a neodymium salt with an aqueous solution of a ferrous salt to yield a feed solution;(b) mixing the feed solution with a precipitant to form a co-precipitate product, wherein the precipitant comprises aqueous ammonium hydroxide, aqueous ammonium carbonate and a soluble boron compound;(c) removing oxygen from the co-precipitate product by introducing a hydrogen stream to the co-precipitate product and removing an effluent therefrom, wherein the hydrogen stream is introduced until there is no moisture in the effluent and only oxygen is left over in the product apart from the alloy elements, thereby forming a hydrogen pre-reduction product;(d) intimately mixing the hydrogen pre-reduction product with at least one of metallic calcium and calcium hydride, thereby forming a calcium reduction-diffusion product;(e) rinsing and drying the calcium reduction-diffusion product; and(f) manufacturing an alloy powder from the calcium reduction-diffusion product.