Fabrication of ceramic-metal composites with percolation of phases using GPI

Al₂O₃/AlSi12CuMgNi composites were fabricated using gas-pressure infiltration (T=700°C, p=4 MPa) of an aluminium alloy into alumina performs. Volume fraction of the ceramic phase was up to 30%, while the pore sizes of the ceramic preforms varied from 300 to 1000 μm. Ceramic preforms were formed by method of copying the cellular structure of the polymer matrix. The results of the X-ray tomography proved very good infiltration of the pores by the aluminium alloy. Residual porosity is approximately 1 vol%. Image analysis has been used to evaluate the specific surface fraction of the interphase boundaries (Sv). The presented results of the studies show the effect of the surface fraction of the interphase boundaries of ceramic-metal on the composite compressive strength, hardness and Young's modulus. The composites microstructure was studied using scanning electron microscopy (SEM). SEM investigations proved that the pores are almost fully filled by the aluminium alloy. The obtained microstructure with percolation of ceramic and metal phases gives the composites high mechanical properties together with the ability to absorb the strain energy. Compression tests for the obtained composites were carried out and Young's modulus was measured by the application of the DIC (Digital Image Correlation) method. Moreover, Brinell hardness tests were performed. Gaspressure infiltration (GPI) allowed to fabricate composites with high compressive strength and stiffness.