Effect of wheel speed on the microstructures and magnetic properties of rapidly solidified Sm–Co alloys

• Published in: Journal of alloys and compounds Vol. 502; no. 1; pp. 63 - 67
• Main Authors: Aich, S., Shield, J.E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 16-07-2010; Elsevier
• Subjects: Alloys; Coercive force; Coercivity; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Exchange and superexchange interactions; Magnetic measurements; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Melt spinning; Metals; Permanent magnets; Physics; Precipitates; Precipitation; Remanence; Studies of specific magnetic materials; Wheels; Magnetic measurements; Metals; Permanent magnets; Grain size; Samarium alloys; Annealing; FCC lattices; Magnetization; Metastable phases; Melt spinning; Precipitates; Spring exchange magnet; Rapid solidification; Coercive force; Flow planar casting; Microstructure; Cobalt alloys; Exchange interactions; Magnetic properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.04.126

Melt-spinning of Sm
11Co
89 alloys modified with Nb and C resulted in the formation of the metastable (1:7) structure irrespective of the variations in wheel speed (20–60
m/s), with the formation of fcc-Co phase observed at
v
=
60

m/s
. At higher wheel speed the higher chances of formation of Co precipitate and the reduced size of Co precipitates helped to improve the remanence. Moreover, wheel speeds up to 50
m/s resulted in refined (1:7) grain sizes and thus resulted in higher coercivity. At extremely high wheel speed
(
v
=
60

m/s
)
, short contact time with the wheel for the molten pool caused in-flight annealing and thus resulted in coarser grain and lower coercivity value. Most of the alloys exhibited a high reduced remanence ratio (∼0.7) indicating significant exchange–spring interactions between the grains. At higher wheel speed the magnetization process was dominated by pinning mechanism.