| 摘要 |
PROBLEM TO BE SOLVED: To impart excellent magnetic properties to a magnet by rapidly cooling an alloy melt mainly composed of Pr, Fe, B, or the like, by a rapid cooling roll and preparing an alloy thin strip composed of a four phase coexistent region of a specified ratio, fine chill crystals, a Pr-enriched phase, or the like. SOLUTION: In this alloy thin strip, an alloy melt mainly composed of R (such as Pr), T (such as Fe) and B is rapidly cooled by a rapid cooling roll, the ratio of a four phase coexistent region in which an α-Fe phase of 0.1 to 20 μm average grain size, an R-enriched layer of 0.1 to 20 μm, an RxT4B4 phase (x=1+ε, and ε is the constant decided by R) of 0.1 to 10 μm and an R2T14B phase of 0.1 to 20 μm are finely dispersed is 1 to 10 vol.% in the total volume, and the ratio of fine chill crystals of <=3 μm average grain size present on the cooling face in contact with the rapid cooling roll is 1 to 30 vol.% in the whole volume. Moreover, in the thin strip, the balance other than the four phase coexistent region and chill crystals is composed of an R-enriched phase, an RxT4B4 phase and an R2T14B phase or of an R-enriched phase and an R2T14B phase. |
