Role of the residual amorphous phase in the intergranular magnetic coupling in nanocrystalline magnetic alloys

The temperature dependence of the coercivity (H-c) in nanocrystalline Fe91Z r7B2 samples with various fractions of the residual amorphous phase (V-am) has been investigated with particular attention paid to the role of the res idual amorphous phase in determining the intergranular magnetic coupling. H -c in the temperature range above the Curie temperature of the residual amo rphous phase (T-C(am)) decreases significantly with decreasing V-am. On the contrary, H-c in the temperature range much less than T-c(am) increases sl ightly with decreasing V-am. These result suggest that the intergranular ma gnetic coupling is dominated by the intergranular distance in the temperatu re range > T-C(am) whereas it is independent of the intergranular distance well below T-C(am). (C) 1999 Elsevier Science B.V. All rights reserved.