Formation of MgO nanorods in the reaction zone of a Mg–CuO powder mixture by in-situ reaction

Abstract

We report the in-situ formation of MgO nanorods during sintering of a Mg–20 wt% CuO powder mixture at 450°C. After sintering, we identified three regions with distinct microstructures in the reaction zone between the Mg grain and the newly formed Cu grain. Region I contained MgO nanorods and Cu nanoparticles, region II was composed of MgO nanorods, while larger nanometre-sized MgO crystals were found in region III. The MgO nanorods were single crystals with a diameter of about 20 nm and a length of about 100 nm. The growth of these nanorods was controlled by the vapour–solid mechanism. The progressive change in morphology of the MgO phase had induced a hardness gradient across the reaction zone. As a result, the interfacial bonding between the major phases in the sintered product was enhanced.

Acknowledgements

This work was supported by the Direct Allocation Grant from The Chinese University of Hong Kong (project 2060195), and by the RGC-2001 Earmarked Research Grant (project 2150303) of the Hong Kong Special Administrative Region Government.