On nanostructured molybdenum-copper composites produced by high-pressure torsion

Year: 
2017
Month: 
5
Day: 
9
Pages: 
9872-9883
DOI: 
10.1007/s10853-017-1142-2
Type: 
Journal Articles
Journal: 
Journal of Materials Science
Volume: 
52
Abstract: 

Nanostructured 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 and ~10-20nm, 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.