Sintering of Cu-Al2O3 nano-composite powders produced by a thermochemical route

This paper presents the synthesis of nano-composite Cu-Al2O3 powder by a thermochemical method and sintering, with a comparative analysis of the mecha- nical and electrical properties of the obtained solid samples. Nano-crystalline Cu-Al2O3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homo- genization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and ther- mogravimetric (DTA-TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20-50 nm, with a noticeable presence of agglomera- tes. The composite powders were characterized by a homogenous distribution of Al2O3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature ran- ge from 800 to 900 °C for up to 120 min. Characterization of the Cu-Al2O3 sinte- red system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB) analysis, as well as by EDS. The obtained nano-composite, the struc- ture of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper mat- rix, with exceptional effects of reinforcement and an excellent combination of me- chanical and electrical properties.