The structure and magnetic properties of mechanically milled Nd7Dy1Fe7
8Co10B4 have been studied. As-milled samples consist of a mixture of a
n amorphous phase and a b.c.c. FeCo phase and exhibit soft magnetic be
haviour. Optimally annealed samples contain a nanocrystalline mixture
of (NdDy)(2)(FeCo)(14)B and b.c.c. FeCo with an average grain size of
20 nm. Enhanced remanence values of up to 120 emu g(-1) and coercivity
of 5.3 kOe are obtained in isotropic nanocomposite samples containing
similar to 40vol.% of soft phase. The magnetic behaviour is associate
d with exchange coupling between the hard and soft magnetic phases. (C
) 1997 Elsevier Science Ltd.