The invention provides a method for preparing a high-
coercivity sintered
neodymium-iron-
boron magnet, and belongs to the technical field of
rare earth permanent
magnet material preparation, and the method comprises the following steps: 1, taking the sintered
neodymium-iron-
boron magnet as a base material, and removing an
oxide layer through alkali washing deoiling, ultrasonic
water washing and acid
pickling cleaning; 2, taking the Pr-Dy-Cu-Ga
quaternary alloy as a
diffusion source, and
cutting the Pr-Dy-Cu-Ga
quaternary alloy into slices; 3, attaching the
thin sheet to the surface of a base material for
diffusion heat treatment; fourthly, low-temperature
tempering is conducted; 5, testing a
room temperature demagnetization curve of the sample; light
rare earth Pr replaces a part of heavy
rare earth Dy and is matched with Cu and Ga elements in a certain proportion to be smelted to obtain
quaternary alloy, the
quaternary alloy with low heavy rare earth serves as a
diffusion source, the microscopic characteristics of the magnet are improved,
grain boundary phase distribution is optimized, and under the condition that residual
magnetism and the maximum
magnetic energy product are slightly reduced, the coercive force of the sintered
neodymium-iron-
boron magnet is improved; and
terbium and
dysprosium are not used, so that the use amount of heavy rare earth elements and the production cost are reduced.