Investigation of Interaction Effects in a Nanocrystalline Nd2Fe14B+αFe Composite System

ORLANDO BILLONI; SILVIA E. URRETA; LUIS FABIETTI

MATERIALS SCIENCE FORUM

Trans Tech Publication, Switzerland.

Año: 1999 p. 273 - 277

0255-5476

The interactions responsible for the observed properties in a two-phase Nd2Fe14B + aFe composite are investigated. These interactions are demostrated by irreversible magnetization curves strongle dependent on the magnetic configuration of the system. Their effects are analyzed by a) considering the changes in the effective distributions of critical fields for reversion of magnetization in different configurations and b) assuming that they are described by a uniform mean interaction field superimposed to the applied field. Both descriptions lead to confirm the results of micromagnetic calculations in the sense that the magnetic behavior of these fined grained composites is governed by exchange interactions. As the grain decreases, two competitive effects are found to determine the grain size dependence of the coercivity: the exchange hardering of the soft phase and the exchange weakening of the hard phase.