Elimination of the non-recrystallised regions in the extruded MnAl-C-Ni magnet using pulverised melt-spun ribbons

MnAl-C-Ni magnets with maximum energy products, (BH)max >= 42 kJ m-3, were produced by hot extruding pulverised melt-spun ribbons. The small diameter of the columnar grains in the as-spun ribbons (1 mu m <_ d <_ 6 mu m), restricted the maximum size of the -r-phase grains, which formed during the holding process at 700 degrees C before the extrusion. The absence of non-recrystallised regions in the extruded material made from ribbons produced at high wheel speed was attributed to this smaller initial -r-phase grain size (1 mu m <_ d <_ 2 mu m) and resulted in an enhancement of the squareness factor of the demagnetisation curve. (c) 2021 The Authors. Published by Elsevier B.V. CC_BY_4.0