Effects of boron substitution on the structural and magnetic properties of melt-spun Sm(Co,Fe,Zr) 7.5 and Sm(Co,Fe,Zr,Cu) 7.5 magnets

Abstract

In this work we examine the effect of small boron substitution (x=0,0.005,0.010,0.015) on the structural and magnetic properties of Sm(Co 0.86-xFe 0.1Zr 0.04B x) 7.5 and Sm(Co 0.74-xFe 0.1Cu 0.12Zr 0.04B x) 7.5 melt-spun samples, as a function of wheel speed and annealing conditions. Boron substituted as-spun ribbons are found to have increased coercivity, Hc>5kOe, and small grain size of 60-100 nm. For copper containing samples, the highest coercivity (Hc=16.3kOe) was obtained in as-spun ribbons with x=0.015. In samples without copper the coercivity increased after short annealing (Hc=12kOe for x=0.015). The large coercivities are attributed to a fine microstructure consisting mainly of hexagonal TbCu 7-type phase and a small amount of soft-phase grains. © 2002 American Institute of Physics.