Abstract: The present invention relates to an alloy with composition of RE-Fe-M-B as defined herein, wherein said alloy comprises at least 80 vol % RE2Fe14B phase, the average crystal grain size of the RE2Fe14B phase is in the range of about 20 nm to about 40 nm, and the alloy is an alloy ribbon having a width measured from a left edge to a center portion to a right edge, and the average crystal RE2Fe14B grain size difference between the center portion, and left and right edges of said alloy ribbon is less than 20%. The present invention also relates to a method for preparing an alloy ribbon with composition of RE-Fe-M-B as defined herein comprising the steps of: (i) ejecting a melt of the alloy with composition of RE-Fe-M-B onto a rotating wheel at a mass flow rate of about 0.2 kg/min to about 1.