Effect of microwave sintering over vacuum and conventional sintering of Cu based nanocomposites

The blend compositions of Cu₉₉Cr₁ (All the compositions are in atom% until otherwise mentioned.), Cu₉₄Cr ₆, Cu₉₉Cr₁-4 wt.% SiC (average particle size ∼30 nm) and Cu₉₄Cr₆-4 wt.% SiC were ball-milled for 50 h in a stainless steel grinding media. The structural investigation and phase evolution during milling of the same compositions have already been reported in elsewhere ([28]). In the present study, we are reporting effect of microwave sintering on mechanical properties and electrical conductivity over vacuum and conventional sintering carried out at 900 C. Relative densification and grain coarsening characteristics were investigated and compared. The microstructural features were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The mechanical properties, namely, Vickers hardness and wear resistance, and electrical conductivity were studied to investigate the suitability of the materials for electrical contact applications. The best combination of mechanical properties and electrical conductivity was obtained for microwave sintered specimens. This is possibly due to the enhanced densification and better grain size distribution achieved in microwave sintering technique. Difference in the properties is discussed in the light of electron scattering factor and densification in presence of ultra fine SiC particles in the nanocomposites.