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 Pr16Fe76B8 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%).