Mechanical properties of aluminium alloy 6061–Al₂O₃ composites

Abstract

One of the most beneficial property improvements that can be realised using metal matrix composite technology is the ability to increase the relatively low stiffness and hardness of aluminium alloys by the addition of high modulus particles such as Al₂O₃. The stiffness and hardness of the resulting composites increase with increasing volume fraction of particles. Unfortunately, these increases are accompanied by corresponding reductions in the ductility. Because of this compromise in properties with increasing volume fraction, a balanced combination of tensile strength, ductility, creep resistance, toughness, and fatigue resistance must be achieved for successful industrial application. In this regard, mechanical testing of a cast and extruded 6061 aluminium alloy containing 0, 10, or 20 vol.-%Al₂O₃ particles has been carried out with emphasis on measuring the properties which would be the most important for an application such as steam turbine blading. In addition to an increased room temperature yield strength, the composites also exhibited improved water droplet erosion resistance, which increased with increasing volume fraction and decreasing particle size. In contrast, there was no beneficial strengthening at elevated temperatures and the creep resistance of the composites at 150°C was actually reduced in comparison with the unreinforced alloy. It is expected that the low cost, increasing availability, and continuing assimilation of property data should lead to increasing industrial use of this class of new materials.

MST/1818