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Aiming for the accelerated screening of promising materials for a variety of engineering applications efficiently and cost-effectively, a novel high-throughput micro-synthesis of a combinatorial material library through hot isostatic pressing was reported herein. As Co, Fe and Ni are the most common base and alloying elements in metallic alloys and particularly in high entropy alloys, a Co-Fe-Ni ternary alloy system was selected for the study. Using high-purity elemental metal powders as stock materials, 19 combinatorial alloy compositions were designed, and their powder mixtures were placed and vacuum sealed in the cell space of a set of customized honeycomb arrays made of Ni or Ti foils. Subsequent consolidation was conducted under hot isostatic pressing at 1050 °C at 120 MPa for 10 hours. Each of the as-made bulk alloys was characterized by microscopy and spectroscopy, exhibited no macro defects, had actual compositions comparable to the nominal ones, and generated phase constituients and microstructure comparable to these via traditional processes for bulk alloys. The composition and phase constitution of these alloys were systematically characterized, and the discrepencies comparing to historical data were ascribed to the thermodynamic and kinetic driving forces in the processing. The present method, i.e. high-throughput synthesis and characterization of a combinatorial materials library in bulk alloys, demonstrated a new way for screening alloy compositions, microstructures and properties.

This study investigated the effects of microwave sintering on the microstructures and properties of copper-rGO composites. Graphene oxide was coated onto copper particles by wet ball milling, and copper-rGO composites were formed upon microwave sintering in an argon atmosphere. Scanning electron microscopy was then used to observe the mixing in the ball-milled composite powder, and the morphology of the bulk composite after microwave sintering. Raman spectra revealed how graphene oxide changed with ball milling and with microwave sintering. The microhardness, electrical conductivity, and thermal conductivity of the composite were also measured. The results showed that graphene oxide and copper particles were well combined and uniformly distributed after wet ball milling. The overall microhardness of microwave-sintered samples was 81.1 HV, which was 14.2% greater than that of pure copper (71 HV). After microwave sintering, the microhardness of the samples in areas showing copper oxide precipitates with eutectic structures was 89.5 HV, whereas the microhardness of the precipitate-free areas was 70.6 HV. The electrical conductivity of the samples was 87.10 IACS%, and their thermal conductivity was 391.62 W·m−1·K−1.