Rare earth magnet precursor or rare earth magnet molded body having roughened structure on surface and method for manufacturing same

A rare earth magnet material having a roughened structure on a surface,

• wherein the surface having the roughened structure comprises a plurality of circular recesses, a plurality of annular protrusions formed around the plurality of circular recesses, and recesses surrounded by adjacent ones of the plurality of annular protrusions, and all or some of the annular protrusions have a hook-shaped projecting part projected into the inner circular recess and/or a plurality of projections projecting outward from outer circumferential wall sections thereof, and
• wherein recesses and protrusions satisfying at least one of the following requirements (a) to (c) are formed in the surface having the roughened structure:
• (a) an arithmetic mean height (Sa) (ISO 25178) from 5 to 300 μm,
• (b) a maximum height (Sz) (ISO 25178) from 50 to 1500 μm, and
• (c) a developed interfacial area ratio (Sdr) (ISO 25178) from 0.3 to 12.

A rare earth magnet material having a roughened structure in a surface,

• wherein the surface having the roughened structure comprises a plurality of independent protrusions each surrounded by a recess or a plurality of independent recesses and a protrusion surrounding each recess,
• wherein the plurality of independent protrusions or the plurality of independent recesses comprise a first group of linear protrusions and linear recesses in which a plurality of linear protrusions formed in a length direction and a plurality of linear recesses formed in the same direction as the length direction are alternately formed in a direction orthogonal to the length direction at the same or different intervals and a second group of a plurality of linear protrusions and a plurality of linear recesses alternately formed at the same or different intervals in a direction to intersect the first group of linear protrusions and linear recesses,
• wherein the intervals between widthwise center positions of the linear protrusions in the first group and the intervals between widthwise center positions of the linear recesses in the first group, and the intervals between widthwise center positions of the linear protrusions in the second group and the intervals between widthwise center positions of the linear recesses in the second group are in a range from 0.03 to 1.0 mm, and
• wherein recesses and protrusions satisfying at least one of the following requirements (a′) to (c′) are formed:
• (a′) an arithmetic mean height (Sa) (ISO 25178) from 5 to 150 μm,
• (b′) a maximum height (Sz) (ISO 25178) from 50 to 700 μm, and
• (c′) a developed interfacial area ratio (Sdr) (ISO 25178) from 0.3 to 6.