The effect of mechanical milling on the soft magnetic properties of amorphous FINEMET alloy

• Published in: Journal of magnetism and magnetic materials Vol. 381; pp. 322 - 327
• Main Authors: Gheiratmand, T., Hosseini, H.R. Madaah, Davami, P., Gjoka, M., Song, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2015
• Subjects: Amorphous materials; Crystal structure; Curie temperature; Ferrous alloys; Magnetic properties; Magnetization; Mechanical milling; Melt spinning; Mossbauer spectroscopy; Mössbauer spectroscopy; Order disorder; Ribbons; Melt spinning; Amorphous materials; Mechanical milling; Mössbauer spectroscopy; Curie temperature
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2015.01.016

The effect of milling time on the magnetic properties of FINEMET amorphous ribbons has been investigated using X-ray diffraction, Mössbauer spectroscopy, thermo-magnetic measurements, transmission electron microscopy and SQUID magnetometery. Ribbons were melt-spun at a wheel speed of 38ms-1 and then mechanically milled for different periods up to 45min. The results showed that the partially crystallization of the amorphous powder occurs during milling. TEM observations confirmed the formation of small volume fraction of the crystalline phase with ~9nm crystallite size in the amorphous matrix for the ribbon milled for 45min. Thermo-magnetic measurements indicated the enhancement of the Curie temperature of amorphous phase during milling which is due to the annihilation of free volumes and microstructural ordering. The Hopkinson effect led to the monotonic increase of magnetization with respect to the temperature before reaching the Curie temperature of the milled samples. Moreover; the magnetization increased with the formation of the Fe(Si) phase while the coercivity decreased. Mössbauer spectroscopy and thermo-magnetic measurements revealed the existence of 13% Fe in crystalline phase. The composition of crystalline phase was determined as Fe–16.5Si. Hyperfine field values increased with milling time, suggesting the ordering of the structure and enhancement of the number of Fe–Fe atomic pairs in the crystalline phase comparing to the primary amorphous ribbon. •Effect of crystallization of amorphous FINEMET during milling has been investigated.•Milling of amorphous ribbons for 45min caused the formation of nano crystals.•Annihilation of free volumes increased the Curie temperature of amorphous phase.•Hyperfine field values increased with milling time suggesting ordering of the structure.•Hopkinson effect led to the monotonic increase in magnetization before Tc.