Strengthening of copper with homogeneous dispersion of nanoscale tungsten particles fabricated by spark plasma sintering

Highlights: • Cu–W alloys with high strength and excellent thermal conductivity were fabricated. • W nanoparticles significantly refine the grains and improve the strength of Cu. • The average particle size of W is 43 nm and the grain size of Cu–W is 500–900 nm. Copper alloys are promising heat sink materials in future fusion reactors owing to the high thermal conductivity and good mechanical properties at medium temperatures. In the present study, aiming at enhancing the strength of copper while keeping the high thermal conductivity, nanoscale W particle dispersion strengthened Cu alloys with different W content of 2 at% (2.6 vol%), 5 at% (6.5 vol%) and 8 at% (10.3 vol%) were fabricated through ball-milling and spark plasma sintering (SPS). The effects of nanoscale W particles on the microstructure, mechanical properties and thermal conductivity of the Cu–W alloys were investigated. The average size of tungsten particles dispersed in copper matrix is 43 nm. The dispersion of W nanoparticles in copper could significantly refine the grain and improve the strength of Cu alloys. The average grain size of Cu-2at%W, Cu-5at%W and Cu-8at%W is as small as 0.84 μm, 0.65 μm and 0.54 μm, respectively. The tensile strength of Cu-8at%W reaches 495 MPa and the elongation is 10.6% at room temperature. The grain size refinement of Cu–W alloys can be attributed to the pinning effects of nanoscale W particles dispersed in the Cu matrix. Although the addition of W nanoparticles leads to a decrease in thermal conductivity, the thermal conductivity for all Cu–W samples is still above 300 Wm^-1K^-1 at room temperature.