Patent ID: 7594972
Filing Date: 2009-09-29
Classification: B22F,C22C,C23C,H01F

Abstract:
1. A cast alloy lump for R-T-B type sintered magnets, comprising an R 2 T 14 B columnar crystal and an R-rich phase, wherein R is at least one rare earth element including Y, T is Fe or Fe with at least one transition metal element except for Fe, and B is boron or boron with carbon, wherein in the as-cast state, R-rich phases having a line or rod shape, with the width direction of the line or rod being a short axis direction, are dispersed in a cross section, and an area percentage of the region where R 2 T 14 B columnar crystal grains have a length of 500 μm or more in a long axis direction and a length of 50 μm or more in the short axis direction is 10% or more of the entire alloy, and wherein the aspect ratio of the R-rich phase is 10 or more.