FATIGUE AND COMPRESSION CHARACTERISTICS OF Al 6061–B₄C COMPOSITE MATERIALS

Abstract

Aluminum matrix composites reinforced with boron carbide are a kind of materials that are widely used because of high strength, low density, and improved tribological properties. In this study, mechanical properties of Al 6061–B₄C composites reinforced with B₄C of three different particle sizes were investigated. In the Al 6061–B₄C composite materials, produced by the powder metallurgy methods (extrusion of billets obtained by sintering at temperature of 550 °C under pressure of 450 MPa), the change of mechanical properties such as hardness, compressive strength, and fatigue life, related to B₄C particle size and the applied heat treatment mode (aging at 180 °C for 5 h), were investigated. The hardness of the materials is increased with B₄C grain size and the heat treatment. After the heat treatment, the fatigue life of Al 6061–B₄C (3 µm) material increases slightly, while that of the composite materials decreases with larger size of B₄C reinforcement. The fatigue life of the composite materials reinforced with a larger grain size B₄C is reduced by heat treatment. While the compression test data of untreated composite materials were similar to each other, the heat treatment increased these values in all samples. The highest increase in the compression strength was observed in the composite reinforced with 17 µm sized B₄C. The addition of graphite reduces the deformation ability of the composites.