| Effect of grain size on the coercive field of hard and soft magnetic materials Marcos De Campos1; Jose Adilson De Castro1; 1UFF - FEDERAL FLUMINENSE UNIVERSITY, Volta Redonda, Brazil; PAPER: 208/SISAM/Regular (Oral) SCHEDULED: 17:50/Thu. 24 Oct. 2019/Dr. Christian Bernard ABSTRACT: Several models for predicting the effect of grain size on the coercive field are presented and discussed. For small grain size, near the mono domain grain size, a law Hc ~ 1 / D0.5 has been observed [1]. Here, Hc is the coercive field and D is the grain size. For sintered NdFeB and Strontium ferrites, the Hc ~ 1 / D0.5 law has been experimentally confirmed. For very large grain size, however, a case of soft magnetic materials as electric steels, a Hc ~ 1 / D is observed [2]. The origin of these different behaviors is discussed [3]. We also discuss how to evaluate the effect of grain size on the coercive field by means of a nucleation model. References: [1] M. F de Campos. Effect of Grain Size on the Coercivity of Sintered NdFeB Magnets. Materials Science Forum, v. 660, p. 284-289, 2010.<br />[2] M. F. de Campos. A General Coercivity Model for Soft Magnetic Materials. Materials Science Forum, v. 727-728, p. 157-162, 2012.<br />[3] M. F. de Campos. Coercivity Mechanism in Hard and Soft Sintered Magnetic Materials. Materials Science Forum , v. 802, p. 563-568, 2014. |
