R-T-B-M sintered magnet and manufacturing method thereof

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The present invention provides an R-T-B-M sintered magnet made from an R-T-B-M alloy via a series of processes steps such as melting, hydrogen decrepitation, milling, molding, sintering, and aging treatment. The process steps of hydrogen decrepitation, milling, and molding are performed under inert conditions. Oxygen is avoided during the milling process. The ultrafine powders, which are abundant in rare earth elements, are not required to be wiped off. R is at least one element selected from rare earth elements including Sc and Y. T is at least one element selected from Fe and Co. B means boron. M is at least one element selected from Ti, Ni, Nb, Al, V, Mn, Sn, Ca, Mg, Pb, Sb, Zn, Si, Zr, Cr, Cu, Ga, Mo, W and Ta. The weight content of the related elements are : 29%≤R≤35%, 62%≤T≤70%, 0.1%≤M≤1.8%, 0.9%≤B≤1.2%. The weight content of oxygen in the magnet is equal to or less than 0.07%.