The effect of key process parameters on crystallographic texture and magnetic properties of PrFeB HD sintered magnets produced using high-energy milling

Abstract

A combination of hydrogen decrepitation and planetary ball milling has been used to produce sintered Pr 16Fe 76B 8 magnets. The effects of key process parameters and texture have been studied. The alignment degree (〈cos Θ〉) has been investigated by X-ray pole figure analysis using the (0 0 4) reflection. Magnets prepared from the alloy decrepitated for 3.6 ks and milled for 1.8 ks exhibited a low degree of crystal alignment (0.71±0.02) due to polycrystalline particles. Increasing the milling time to 4.5ks has led to an improvement in 〈cos Θ〉 to 0.84±0.02. This has been ascribed to the smaller particle size with a narrower size distribution as well as a more favorable particle shape for orientation. Superior alignment degree (〈cos Θ〉=0.88±0.02) has been achieved for the sintered magnet from the alloy decrepitated for 120 s and milled for 5.4 ks. This particular processing condition has led to a magnet with (BH) max=250±5 kJ m −3, value found in magnets produced using roller ball milling, with the advantage of a reduced milling time (about 90%).