J. Naser et al., DISPERSION HARDENING OF METALS BY NANOSCALED CERAMIC POWDERS, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 234, 1997, pp. 467-469
Nanoscaled Al2O3-powders (n-Al2O3) with a median particle diameter of
14 nm are distributed in microscaled copper powders by ball milling in
a planetary mill followed by uniaxially hot pressing. The microstruct
ures of the samples are analysed by SEM and EDX investigations and the
hardness of the specimens is determined before and after heat treatme
nts of the composites. The results on the produced Cu/n-Al2O3 composit
es show that the nanoparticles are largely homogeneously distributed i
n the matrix grains, that the matrix grains are stabilised against gro
wth even after heat treatments close to the melting temperature of Cu,
and that the hardness of the sample is largely maintained after heat
treatment. The results show that mechanical alloying of metal micropow
ders with oxide ceramic nanopowders can produce dispersion-strengthene
d materials. The mechanical alloying with n-powders can be easily appl
ied to systems which cannot be dispersion-strengthened with n-oxide ce
ramics by other methods, e.g. internal oxidation, The last is shown by
dispersion-strengthening of magnesium with n-Al2O3. (C) 1997 Elsevier
Science S.A.