Magnetostriction of nanocrystalline (Fe,Co)-Si-B-P-Cu alloys

Amorphous ribbons of composition Fe85.2-xCoxSi0.5B9.5P4Cu0.8 (x = 0 at% and 4 at%) have been flash annealed for 10 s at temperatures between 350 degrees C and 540 degrees C. Above about 400 degrees C a nanocrystalline state of bcc Fe(Co) is formed with a crystalline fraction of 50-55% and grain sizes of about 16-18 nm. The optimum nanocrystalline state reveals a saturation polarization up to J(s)=1.82 T-1.83 T and a coercivity as low as 3-5 A m(-1). The present paper complements the so far missing magnetostriction data for these alloys. Magnetostriction decreases from initially 40 ppm in the as cast amorphous state to about 14 ppm (x = 0 at%) and 19 ppm (x = 4 at%), respectively, after formation of the fully developed nanocrystalline state. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.