Effect of Pulse Plasma Sintering Temperature on Microstructure and Mechanical Properties of Al2O3-Cu Composites

TL;DR

This paper studies how different sintering temperatures affect the structure and strength of Al2O3-Cu composites made using pulse plasma sintering.

Contribution

The study demonstrates the effectiveness of pulse plasma sintering in producing dense Al2O3-Cu composites with controlled microstructure and mechanical properties.

Findings

All composites achieved over 99% relative density, with no secondary reaction products.

Higher sintering temperatures increased grain size in the alumina matrix and reduced copper dispersion.

Maximum fracture toughness was observed at 1400 °C, while optimal compressive strength was achieved at 1300 °C.

Abstract

Al2O3-Cu ceramic-metal composites containing 2.5 vol.% of a metallic phase were fabricated using the Pulse Plasma Sintering (PPS) method in order to evaluate the influence of sintering temperature on densification, microstructure, and mechanical performance. Consolidation was carried out at 1200 °C, 1250 °C, 1300 °C, and 1400 °C under uniaxial pressure with a short sintering time of 3 min. Regardless of the processing temperature, all composites exhibited very high relative densities exceeding 99% of the theoretical value, indicating the high efficiency of PPS in densifying Al2O3-Cu systems while suppressing copper leakage. X-ray diffraction confirmed the presence of only two phases, Al2O3 and Cu, with no secondary reaction products. Microstructural observations revealed irregular copper particles and areas of dispersed metallic phase, whose proportion decreased with increasing sintering temperature due to accelerated matrix densification and copper immobilization. Grain growth in the alumina matrix was strongly temperature-dependent, with the average equivalent grain diameter increasing from 0.49 µm at 1200 °C to 2.35 µm at 1400 °C. Hardness decreased from 19.5 ± 2.8 GPa to 12.2 ± 1.6 GPa with increasing temperature, whereas fracture toughness reached a maximum of 5.42 ± 0.65 MPa·m0.5 at 1400 °C. The highest strength under monotonic compression conditions was obtained for samples sintered at 1300 °C, indicating an optimal balance between densification and microstructural coarsening. These results demonstrate that PPS is an effective method for producing dense Al2O3-Cu composites with tailored microstructure and mechanical properties.

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