This article presents a comparison of the properties of composites based on aluminum or aluminum alloy (Al4Cu) rein- forced with silicon carbide SiCp. The main objective was to analyze the possibility of producing an Al + Cu alloy matrix by basic powder metallurgy methods and its influence on the final properties of the composite. The composites were produced by pressing and sintering, basic powder metallurgy techniques, in order to reduce the manufacturing costs. Sintering was carried out in nitrogen due to the favorable effect of this atmosphere on the sintering of aluminum-based materials. Silicon carbide SiC was used as the reinforcing phase. The study clearly showed that the use of a matrix made of a mixture of Al and Cu powders results in an almost twofold increase in hardness (from 32 to about 60 HB) and a more than twofold increase in flexural strength (from about 200 to more than 450 MPa). Observations of the microstructure confirmed the diffusion of copper into the aluminum and the facets of the Al2Cu phase.
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The paper presents the results of a study on the microstructure and hardness measurements of Al4Cu-xSiC (x = 5, 10, 20 and 30 wt.%) composites produced by spark plasma sintering (SPS). The sintering process was carried out in an HP D 25/3 plasma sintering furnace in a vacuum atmosphere, with sintering temperatures of 580 and 600°C and a densification pressure of 50 MPa. The heating rate was 100°C/min and the isothermal holding time at the sintering temperature was 2.5 min. As a reference material, the AlCu matrix was sintered under the same conditions. As a result, composites with a near-full density of 96.5-99.5% were obtained. Microstructure studies were performed employing the techniques of light microscopy, scanning, and transmission electron microscopy, along with analysis of the chemical composition in microareas. The test results did not reveal remarkable differences in the microstructure of the investigated composites sintered at 580 and 600°C. The sinters have a fine-grained microstructure with a strengthening phase located at the grain boundaries; locally, pores are visible. Increasing the SiC content in the composites promotes the formation of agglomerates of these particles. It was proven that a higher sintering temperature has a positive effect on the hardness of the studied composites.
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