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Rare-earth permanent magnets plays a vital role on the electromagnetic devices industry. The major applications of this material industrially are in the production of motors for electric and hybrid vehicles and magnetic generators for wind turbines. With the Chinese restriction of rare-earth exportations in 2010, the high prices and the need to substitute the heavy rare-earths (Dy,Tb) in the permanent magnets, there is a global interest in alternatives. In the processing of rare earth permanent magnets, the milling process is a determinant step, controlling and homogenizing the microstructure of the magnet, increasing its properties. The present work evaluates the influence of different high energy planetary ball milling times on the microstructure and the magnetic properties of sintered permanent magnets. The magnets were prepared via conventional powder metallurgy route, using powders obtained by the hydrogen decrepitation process (HD) made in the (Nd, Pr)13.49Fe77.72B6Co1,1Al1,2Nb0,28Cu0,2. Strip-Casting alloy. The milling process was carried under ciclohexane medium, using a High Energy Planetary Mill for a period between 30 and 75 minutes, with regular intervals of 15 minutes at a speed of 200 rpm. The magnets were characterized by Scanning Electron Microscopy (SEM), Dispersive Energy Spectroscopy (EDS), X-ray Diffraction (XRD), and magnetic properties were obtained by Permeameter. The magnet produced with 45 minutes of milling (45-B) presented Br = 1.38 T, intrinsic coercivity iHc = 880 KA.m, maximum energy product BHMÁX = 330 KJ.m , squareness factor SF = 0,95 and alignment degree  = 0,96.

Influência dos parâmetros de processamento na microestrutura e nas propriedades magnéticas de ímãs permanentes de (Nd,Pr)FeB