Electroforming of High-strength Lightweight Nanostructured Aluminum Alloys with Complex Geometries

Electroforming is an inherently appealing additive manufacturing process, with net shape objects “grown” atomic layer by atomic layer.  Devices and component parts that are microns to millimeters in thickness and of micron to meter-scale lateral dimensions can be fabricated with complex 3D geometries.  Xtalic employs a novel pulse plating technology to fabricate nanostructured aluminum alloys.  The main difference between Xtalic’s process and typical electroplating is the use of periodic pulse reverse waveforms. Our waveforms consist of different pulses, where each pulse is designed to exert a specific function on the surface atoms of the workpiece during the electrodeposition process.  Forward pulses are utilized to deposit monolayers of atoms at a controlled rate, while reverse pulses are used to selectively remove high energy non-equilibrium adatoms from the surface; pauses are employed to allow adatoms to diffuse and relax into equilibrium positions.  By manipulating the electrodeposition process at the atomic level, we engineer an array of structures in the Aluminum-Manganese system. The Al-Mn system exhibits tunable grain sizes that span multiple orders of magnitude from micrometers down to nanometers and further down to the amorphous limit.  What is more, the novel alloys exhibit unprecedented combinations of low density, high strength (>600 MPa) and good ductility (>8%).  By formulating bath chemistry that suppresses dendrite formation, enables fabrication of thick coherent parts (>0.1mm), and developing methods to activate substrates of arbitrary complex geometries, we have demonstrated the ability to fabricate net-shape articles.  This process is highly versatile; the substrates can be encapsulated to form composite articles, or they can be removed to form free-standing net-shape nanostructured Al alloy products.  Such additively manufactured electrodeposited parts can find applications in areas such as medical devices, semiconductor testing, military fuzing components, inertial sensing and MEMS devices.