Fine grain rare earth alloy cast strip, preparation method thereof, and a rotary cooling roll device

An alloy cast strip preparation method comprising:

• performing a melting process including:
• placing rust-removed alloy raw material in a crucible placed in an induction melting furnace;
• excluding impurity gas adsorbed by the alloy raw material;
• controlling a power of the induction melting furnace to perform a cyclic heat treatment to completely melt the alloy raw material before a surface temperature of a melt obtained by melting the alloy raw material is raised to 1300° C.;
• after the alloy raw material is melted, adjusting the power of the induction melting furnace to stabilize the surface temperature of the melt at a temperature in a range from 1400° C. to 1500° C.;
• and
• performing a casting cooling process including:
• arranging the melt uniformly and smoothly on a surface of a rotary cooling roll;
• and
• performing casting cooling on the melt to obtain an alloy cast strip, while controlling a surface linear velocity of the rotary cooling roll to be from 1.5 m/s to 2.25 m/s;
• wherein:
• main components of the alloy cast strip include a rare earth R, an additive element T, iron Fe, and boron B;
• R is one or more of La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Sc, and Y;
• T is one or more of Co, Ni, Cu, Mn, Cr, Ga, V, Ti, Al, Zr, Nb, and Sn;
• and
• a mass ratio of R in the alloy cast strip is in a range from 29% to 35%, a mass ratio of T in the alloy cast strip is smaller than or equal to 5%, and a mass ratio of B in the alloy cast strip is in a range from 0.85% to 1.1%.