Production of bulk nanostructured composites with amorphous matrix revealin
g a significant supercooled liquid region was carried out by die casting an
d mechanical alloying (MA) and subsequent consolidation at elevated tempera
tures. Multiphase materials with different volume fractions of nanocrystall
ine precipitates were prepared from as-cast fully amorphous samples by isot
hermal annealing. In contrast. MA powders were blended with insoluble metal
lic and oxide particles upon milling. The different samples were analyzed b
y X-ray diffraction (XRD), differential scanning calorimetry (DSC), scannin
g electron microscope (SEM) and transmission electron microscopy (TEM), and
viscosity measurements. The mechanical behavior of cast samples was invest
igated using constant (true) compression rate tests at strain rates ranging
from 1 x 10(-5) to 3 x 10(-3) s(-1). The Newtonian viscous how behavior of
the composites at temperatures around T-g is mainly triggered by the homog
eneous how of the supercooled liquid. The easy flow behavior above T-g was
used to consolidate bulk dense specimens from mechanically alloyed composit
e powders. Microhardness measurements at room temperature reveal a substant
ial increase of the hardness of the composites due to the uniform distribut
ion of nanoscale particles. (C) 2001 Elsevier Science B.V. All rights reser
ved.