Effects of Red Mud on Microstructures and Heat Resistance of ZL109 Aluminum Alloy

The effects of red mud on the microstructures and high-temperature tensile properties of the ZL109 aluminum alloy have been investigated. Red mud/ZL109-based composite materials with added red mud (a major byproduct of the aluminum industry), which has been coated with nickel by chemical deposition, have been prepared through gravity casting. The results show that the addition of red mud promotes the alloy’s microstructure and helps to uniformly distribute the eutectic silicon. It also increases the content of heat-resistant phases, such as the Q-Al5Cu2Mg8Si6and γ-Al7Cu4Ni phases. These changes significantly enhance the alloy’s high-temperature tensile properties. The alloy with 1% (wt.%) red mud exhibits the best tensile strength at both room temperature and 350 °C, reaching 295.4 MPa and 143.3 MPa, respectively. The alloy with 1.5% (wt.%) red mud demonstrates excellent performance at 400 °C, achieving a tensile strength of 86.2 MPa through the cut-through method and Orowan mechanism. As a reinforcing material, red mud not only improves the high-temperature resistance of the aluminum alloy but also provides a way to recycle industrial waste. This study offers a new way to address the red mud waste problem and helps develop high-performance, heat-resistant aluminum alloys. It shows the potential of these alloys in high-temperature applications.