Method of producing rare earth alloy flakes

Abstract

When a ribbon is cast by heating raw materials to prepare a molten R-T-B-based alloy and supplying the molten alloy to a chill roll to solidify the molten alloy, the temperature of the molten alloy is adjusted in accordance with at least one of the arithmetic mean roughness Ra and the mean spacing of profile irregularities Sm of the surface of the chill roll, thereby controlling the spacing between adjacent R-rich phases in a crystal structure of resulting alloy flakes to a desired value. This makes it possible to inhibit variations in the crystal structure of the resulting alloy flakes that may occur due to wear of the chill roll. In adjusting the temperature of the molten alloy in accordance with at least one of the arithmetic mean roughness Ra and the mean spacing of profile irregularities Sm, it is preferred that the molten alloy temperature be adjusted using the equation: Δt=−7×(|ΔRa|×|ΔSm|)0.5/α where Δt is an amount of adjustment of the molten alloy temperature (° C.); ΔRa is an amount of change (μm) in the arithmetic mean roughness Ra; ΔSm is an amount of change (μm) in the mean spacing of profile irregularities Sm; and α is a correlation coefficient.

Dependencies are inferred from the claim text.