Although it has attractive properties such as low density, high strength, and corrosion resistance, aluminum alloys are applied more slowly in additive manufacturing (AM) compared to steel, titanium alloys, and superalloys. So far, only a limited amount of aluminum powder has been sold on the market for AM suitable for demanding environments, high pressure, or high temperatures.
Portrait image of Dr. Amir Farkoosh
Dr. Amir Farkoosh is a research collaborator at the Northwestern University Atomic Probe Tomography (NUCAPT) center and the Department of Materials Science and Engineering at the school. His current research focuses on designing advanced heat-resistant aluminum alloys and high-strength steels for additive manufacturing using a combination of experimental and theoretical methods.
In a recent paper, Dr. Farkoosh shared his insights on using 3-D atomic probe tomography (APT) in AM metal research. The discussion is quoted below.
Additive manufacturing (AM), or 3D printing, is an emerging technology used to create 3-D mechanical parts, layer by layer, using geometry as the sole input. Although it is not yet fully mature in terms of technology, rapid prototyping using AM has helped reduce design cycle time and production development costs. By eliminating some barriers to alloy design and traditional manufacturing, AM can create complex geometries that cannot be produced conventionally.
“My concern lies in harnessing the unique properties of AM to develop advanced high-strength aluminum alloys specifically designed for AM, with mechanical properties that surpass those of conventional aluminum alloys.” - Dr. Farkoosh
At NUCAPT, Dr. Farkoosh uses Atom Probe Tomography (APT) primarily in conjunction with other characterization techniques, analytical theory, and computer simulations. For example, in the case of aluminum alloys, these alloys are often enhanced by nano precipitates with varying composition and crystal structure. To elucidate the kinetics of nucleation, growth, transformation, and coarsening of the precipitates as a function of time and temperature, he primarily relies on 3-D APT, providing information about structure and chemistry at the nanoscale.
AM allows for significantly higher cooling rates compared to conventional manufacturing methods, leading to the development of microstructures at significantly smaller length scales. As a result, AM alloys are particularly suitable for examination by APT compared to conventionally produced alloys. In additively manufactured materials, most microstructural features are of smaller magnitude, some of which can be captured in a single APT sample.
APT data is ideal for direct comparison with atomic simulations and modeling to understand their microstructures and dynamics at the atomic scale. Therefore, my APT results are often supplemented by density functional theory calculations and integrated to address correlations, micro/nano structures, and properties. This integration follows the fundamental model of materials science and engineering, particularly focusing on the relationship between micro/nano structures and physical and mechanical properties.