MAGNETICALY SOFT Fe-Co-BASED NANOCRYSTALLINE ALLOYS,
J. Ferenc, A. Wlazl/owska, J. Latuch, T. Kulik, Faculty of Materials
Science and Engineering, Warsaw University of Technology,
ul. Wol/oska 141, 02-507 Warsaw, Poland.
In the present study, Fe[45]Co[43]B[3.6]Cu[1]Zr[7.4-x]AM[x] (x =3.7 or
7.4, AM = Hf or Nb) alloys have been investigated in order to assess
the structure and soft magnetic properties, as well as thermal
stability of the latter. The amorphous alloys were first
nanocrystallised at 500 and 600C, and subsequently exposed to
annealing at 500C for the time up to 700 hours. X-ray diffractometry,
differential scanning calorimetry, transmission electron microscopy
and magnetic hysteresis loop measurement have been applied as
investigation techniques. The crystallisation temperature of the
alloys is between 455 and 525C. Substituting Zr with Nb decreases the
first stage crystallisation temperature and increases the second stage
crystallisation temperature, while Hf acts in the opposite manner, but
its influence is much weaker. The coercive field (H[c]) of the
nanocrystallised alloys increases slightly during the first 50 hours
of annealing, and then remains almost stable up to 1000 h, being
between 35 and 50 A/m. The lowest values of H[c] are observed for the
alloys containing Hf. This may be attributed to the grain size of
a-FeCo, expected to be the smallest for the alloys with Hf. Further
TEM investigations shall be carried out to verify this assumption.
|