Abstract: Disclosed is a sintered body, a sintered permanent magnet and preparation methods. The sintered body comprises Nd2Fe14B crystal phase as a primary phase and a rare earth rich phase as a grain boundary phase and has a composition expressed by composition formula RaBbGacCudAleMfCogFebalance; R is one or more selected from rare earth elements, and R must comprise Nd; M is one or more selected from the group consisting of Zr, Ti, and Nb; a satisfies 13%?a?15.3%; b satisfies 5.4%?b?5.8%; c satisfies 0.05%?c?0.25%; d satisfies 0.08%?d?0.3%; e satisfies 0?e?1.2%; f satisfies 0.08%?f?0.2%; g satisfies 0.8%?g?2.5%; grains in Nd2Fe14B crystal phase have average size L of 4-8 ?m, grain boundary phases have average thickness t with unit of ?m; the relation of t and L is: ?=t/L; and ? is defined as 0.009???0.012. The present disclosure improves diffusion efficiency of heavy rare earth elements RH.
Abstract: The present invention provides a samarium-cobalt magnet and a method for preparing the same. The method comprises mixing an alloy powder with a zirconium powder in an amount of 0.1-0.35 wt % of the weight of the alloy powder to form a mixture. The alloy powder is formed from 10.5-13.5 wt % of samarium, 12.5-15.5 wt % gadolinium, 50-55 wt % of cobalt, 13-17 wt % of iron, 4-10 wt % of copper, and 2-7 wt % of zirconium. The method brings about at low costs a samarium-cobalt magnet having a positive temperature coefficient of remanence.