[P2] Sm-based Magnets & Nitrides

[P2-38] The effect of Fe, Ni substitution on Structural and Magnetic Properties of SmCo₅ Magnets

*Enbang Ti¹, Richard Stuart Sheridan¹, Mangaliso Chaka Obi Brown¹ (1. University of Birmingham (UK))

Keywords:

SmCo5 magnet,Substitution,Phase balance,Manufacturing

Cobalt is a critical material widely used in SmCo magnets due to its excellent magnetic properties, but its high cost and supply chain concerns have driven efforts on reduce the use. This study investigates the structural and magnetic properties of Ni- and Fe- substituted SmCo₅ permanent magnets. The substitution of Ni and Fe for Co aims to reduce the use of cobalt, a critical material, and explore associated magnetic performance changes. To examine the effect of nickel and iron substitution on magnetic properties, samples of SmCo_5-x-yFe_xNi_y (x = 1.4, y = 0.2-1.6) were prepared by arc-melting, followed by hydrogen decrepitation to obtain coarse powder. Knife-milling and ball milling were then used to refine the powder. All samples were sintered in an argon atmosphere with appropriate heat treatment. XRD and SEM analyses showed that the increasing Fe content reduces the formation of the SmCo 1:5 phase, while Ni helps stablise the 1:5 phase. With increasing Ni substitution, the SmCo 2:17 phase was replaced by the 1:5 phase. When Ni was further increased to y = 1.4, the 2:17 phase disappeared, and the phase equilibrium reverted to the form of SmCo₅alloys. This study demonstrates the relationship between phase composition and magnetic property changes. Magnetic characterisation revealed that, compared to SmCo₅, excessive Fe reduced coercivity due to the formation of 2:17 phase. A series of samples was compared to assess the effects of two elements Ni and Fe on magnetic properties.