NANOCRYSTALLIZATION OF Al-Mm-Ni-Fe [ ]ALLOYS BY DEVITRIFICATION,
J.Latuch, H. Dimitrov, T. Kulik, Department of Materials Science and
Engineering, Warsaw University of Technology, 141 Wol/oska Str.,
02-507 Warsaw, Poland.
Amorphous and nanocrystalline structures can easily be obtained in
quaternary systems, containing Al, rare-earth metal and two late
transition metals. Replacement of rare-earth elements by mishmetal
(Mm: Ce-50.3 at. %, La-43.5 at. %, Pr-5.9 at. %, Nd-0.3 at. %) reduces
the cost of investigated materials, as Mm is about 10 times cheaper
than, for example yttrium. Ribbons of Al[92-x]Mm[x]Ni[5]Fe[3] ( x
varies from 3 to 5 at. %) alloys were produced by melt-spinning
technique and fully amorphous ribbons were obtained for alloys,
containing 4 and 5 at.% of Mm. Structures, consisting of
nanoparticles, embedded in amorphous matrix were obtained by
additional isothermal annealing of the initially fully amorphous
alloys.
X-ray diffractometry, transmission electron microscopy and
differential scanning calorimetry were used for characterisation of
the crystallization process and its products.
It was found that the replacement of Al by Mm decreases the difference
between the crystallization temperatures and increases the thermal
stability of the alloys. Volume fraction of nanoparticles was
calculated.
Isothermal annealing was found to be an effective method for
production of nanocrystalline Al-based alloys.
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