FORMATION OF EPSILON-FEXN BN MAGNETIC NANOCOMPOSITE AND ITS THERMODYNAMIC AND KINETIC ANALYSES/

A nanocomposite of nanometer-sized magnetic granular epsilon-FeXN embe dded in a nonmagnetic amorphous boron nitride matrix was prepared by b all milling mixture of alpha-Fe and hexagonal boron nitride in argon a tmosphere. The grain size of the epsilon-FeXN alloy was about 10-20 nm . The nitrogen concentration in the epsilon-FeXN alloy increases with extending milling time. Both thermodynamic calculation and the present experiment show that iron and nitrogen atoms have higher alloying dri ving force than iron and boron atoms. Analyses of thermodynamics and k inetics about formation of the epsilon-FeXN alloy suggested that the f ormation of the epsilon-FeXN alloy is related to amorphization of the hexagonal boron nitride and refinement of the alpha-Fe. II was found f rom the present experiment that a critical grain size of the alpha-Fe reacting with nitrogen in the amorphous boron nitride is about 8 nm.