Influence of reinforcement volume fraction on Ni phase formation and mechanical properties in alumina-metal composites

Justyna Zygmuntowicz, Katarzyna Konopka, Marek Krasnowski, Paulina Piotrkiewicz, Marcin Wachowski, Ireneusz Szachogłuchowicz, Paweł Falkowski

Pre-print pages 1-29

DOI: https://doi.org/10.62753/ctp.2026.04.1.1

keywords: composites, mechanical alloying, slip casting, NiAl-Al2O3 composite powder, fracture toughness

abstract This work reports on the fabrication and characterization of Al2O3-based composites reinforced with NiAl + 30 wt% Al2O3 pre-alloyed powder, synthesized via mechanical alloying. Two composite series were prepared using slip casting: Series I with 2.5 vol.% and Series II with 5.0 vol.% of the reinforcement phase. The samples were sintered at 1450°C in a reducing H₂/N₂ atmosphere. X-ray diffraction revealed that, in both series, after sintering, no NiAl was observed; only Ni was detected. SEM and EDS analyses showed uniform dispersion of the reinforcement. Mechanical testing revealed that increasing the metallic phase reduced the hardness from 17.01 ± 0.61 GPa (Series I) to 15.73 ± 1.51 GPa (Series II), while the fracture toughness slightly improved from 5.14 ± 0.30 to 5.20 ± 0.37 MPa·m⁰.⁵. The compressive strength reached 25 kN and 17 kN for Series I and II, respectively. The results demonstrate that a tailored reinforcement content enables control over the microstructure and mechanical performance in Al2O3-NiAl composites.