Improved hot workability and magnetic properties in NdFeCoGaB hot deformed magnets

Abstract

The hot workability and the magnetic properties of die-upset and backward extruded melt-spun magnets with the composition of Nd/sub 14.2/Fe/sub 80.8/B/sub 5/ (MQP-A), and Nd/sub 13.6/Fe/sub 73.6/Co/sub 6.6/Ga/sub 0.6/B/sub 5.6/ (MQU-F) have been investigated. Magnets of MQU-F powder show an improved hot workability and better magnetic properties compared to the ternary alloy. Remanence, coercivity and energy product of die-upset MQU-F magnets were found to be B/sub /spl tau//=1.3 T, /spl mu//sub 0j/H/sub c/=1.7 T, and (BH)/sub max/=326 kJm/sup -3/, respectively. SEM and TEM investigations revealed a smaller average grain size in MQU-F magnets, which has a positive effect on the hot workability and magnetic properties. Radially oriented ring magnets were produced from both alloys and characterized magnetically. The temperature coefficients of ring magnets were determined to be /spl beta/=(dH/sub c//dT)=-0.6%//spl deg/C and /spl alpha/=(dB/sub /spl tau///dT)=-0.09%//spl deg/C. A higher deformation speed can be used for the production of MQU-F magnets, which should make the process more economic.