Aluminium-Silicon Carbide Particulate MMCs for Stiffness or Wear-critical Aerospace Applications

With the ever-increasing emphasis on decarbonization of the aerospace industry, lightweight components and associated materials selection continues to be a pivotal area in the optimization of existing and conception of future platforms. A significant expansion to existing application areas for the family of light metals can be realized through the development of innovative Metal Matrix Composite (MMC) materials. Reinforcement of aluminum alloys with ceramic particles can produce low-density MMCs with enhanced mechanical and physical properties. Such MMCs can provide attractive solutions for lightweight aerospace structures due to their high specific stiffness and specific strength.

Manufacture of MMCs via a powder metallurgy route utilizing a novel high-energy mixing process has been shown to ensure a homogeneous reinforcement distribution, enabling a refined grain structure and isotropic mechanical and physical properties. This route allows production of MMCs with a homogeneous distribution of ultrafine to nanoscale silicon carbide particles within the matrix alloy, resulting in good machinability via conventional techniques in contrast to most traditional MMC materials. This technology has proven successful with a variety of aluminum matrix alloys and silicon carbide contents ranging 15 to 40 vol.%, with fabrication to forged or extruded forms possible.

Using this powder metallurgy route, 2009 aluminum alloy can be reinforced with 15 vol.% silicon carbide particles – 2009/SiC/15p (5μm). Due to the weight savings versus titanium alloys (~36%), high fatigue and fretting fatigue performance, high wear resistance and low friction characteristics, this MMC is of particular interest for a variety of applications within the aerospace industry including, but not limited to, critical rotating helicopter components, outlet guide vanes, hydraulic/fuel blocks, wheels, and fixed wing structures/skins. Here, the microstructure and properties of this MMC will be presented and discussed with a specific focus on the aerospace industry and associated applications.