  Nano-structured molybdenum-copper composites have been produced through
severe plastic deformation of liquid-metal infiltrated Cu30Mo70 and Cu50Mo50
(wt.%) starting materials. Processing was carried out using high pressure
torsion at room temperature with no subsequent sintering treatment, producing a
porosity-free, ultrafine grained composite. Extensive deformation of the
Cu50Mo50 composite via two-step high-pressure torsion produced equiaxed
nanoscale grains of Mo and Cu with a grain size of 10-15 nm. Identical
treatment of Cu30Mo70 produced a ultrafine, lamellar structure, comprised of Cu
and Mo layers with thicknesses of ~5 nm and ~10-20 nm, respectively and an
interlamellar spacing of 9 nm. This microstructure differs substantially from
that of HPT-deformed Cu-Cr and Cu-W composites, in which the lamellar
microstructure breaks down at high strains. The ultrafine-grained structure and
absence of porosity resulted in composites with Vickers hardness values of 600
for Cu30Mo70 and 475 for Cu50Mo50. The ability to produce Cu30Mo70
nanocomposites with a combination of high strength, and a fine, oriented
microstructure should be of interest for thermoelectric applications.
