US Patent 7211157 Rare-earth alloy, rare-earth sintered magnet, and methods of manufacturing

A rare-earth alloy ingot is produced by melting an alloy composed of 20–30 wt % of a rare-earth constituent which is Sm alone or at least 50 wt % Sm in combination with at least one other rare-earth element, 10–45 wt % of Fe, 1–10 wt % of Cu and 0.5–5 wt % of Zr, with the balance being Co, and quenching the molten alloy in a strip casting process. The strip-cast alloy ingot has a content of 1–200 μm size equiaxed crystal grains of at least 20 vol % and a thickness of 0.05–3 mm. Rare-earth sintered magnets made from such alloys exhibit excellent magnetic properties and can be manufactured under a broad optimal temperature range during sintering and solution treatment.