Coercivity mechanism in SmFeTi rare-earth magnets

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Abstract
The microstructure of SmFeTi magnets has been investigated by electron microscopy and microanalysis. Melt‐spun SmFe10Ti consist of two phases; the hard magnetic SmFe11Ti phase (1:12), with the ThMn12 structure, and α‐Fe. The origin of the Fe formation and its influence on the magnetic behavior are discussed. The measuredtemperature dependence of the coercivity is analyzed in terms of nucleation and pinning mechanisms. It is concluded that both models describe reasonably the temperature dependence of the coercivity in the temperature range 300–500 K, namely that the pinning mechanism predominates at higher temperatures, and the nucleation mechanism at lower temperatures. The microstructure of mechanically alloyed Sm28Fe62Ti10 consists of multiphases. The magnetic properties in these specimens are not determined by the (1:12) phase but a new hard magnetic Sm23Fe73Ti4 phase.