Fabrication and Characterization of Al2O3-Cu Composites Prepared by Uniaxial Pressing

Paulina Piotrkiewicz, Justyna Zygmuntowicz, Marcin Wachowski, Ireneusz Szachogłuchowicz, Waldemar Kaszuwara, Joanna Szymańska

Pre-print pages 1-24

DOI: https://doi.org/10.62753/ctp.2026.02.2.2

keywords: uniaxial pressing, Al2O3-Cu, composites, copper

abstract This study evaluates the fabrication and performance of Al2O3-Cu composites containing 10 vol.% Cu produced by uniaxial pressing (100 MPa) and free sintering in 95% Ar/5% H₂ at 1200–1400°C. A strong temperature–densification relationship was observed. The relative density increased from 81.44% at 1200°C to 97.32% at 1400°C, while the open porosity decreased from 18.27% to 0.15%. Water absorption was reduced from 4.76% to 0.04%, confirming near-complete pore elimination at 1400°C. XRD analysis identified only α-Al2O3 and Cu phases, with no secondary reaction products. SEM observations revealed irregular copper agglomerates formed by liquid-phase migration; however, no macroscopic exudation was detected, indicating effective capillary retention of molten Cu (melting point 1085°C). EDS confirmed sharp phase boundaries without interdiffusion. The optimally sintered composite (1400°C) exhibited a Vickers hardness of 11.7 ± 0.9 GPa and an apparent indentation fracture toughness of 5.90 ± 1.80 MPa·m0.5. Grain-size analysis showed a fine, unimodal alumina distribution predominantly within 0.6-1.2 µm. Digital image correlation during compression revealed heterogeneous strain localization governed by phase distribution. The results demonstrate that dense, mechanically reliable Al2O3-Cu composites can be fabricated via a scalable, cost-effective powder metallurgy route.