Improvements of the magnetic properties of equiaxed Fe-Cr-Co-Mo hard magnets by two-step thermomagnetic treatment

Abstract

Present works describe the developments of the equiaxed Fe-Cr-Co permanent magnets with high coercivity and high energy products. The studied alloy compositions are Fe-(26-32)wt%Cr-15wt%Co-3wt%Mo. The magnetic properties of the alloys have been enhanced by the two-step thermomagnetic treatment (two-step TMT) and by prolonging all of the heat-treatment time. The energy products above 43 kJm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> (5.4MGOe) are obtained for almost all of the studied compositional alloys. Fe- 30%Cr-15%Co-3%Mo alloy gives good magnetic properties as iHc=76.8 kAm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> (960 Oe), (BH)max=49.6 kJm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> (6.2 MGOe). The highest coercivity achieved with Fe-32%Cr- 15%Co-3%Mo alloy is 80.8 kAm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> (1010 Oe).