The approach, led by MIT, involves the 3D printing of a metallic powder strengthened with ceramic nanowire.
A team of MIT-led engineers has reported a simple, inexpensive way to strengthen one of the key materials used in aerospace and energy generation applications – increasing the ability of these materials to withstand extreme conditions such as high temperatures and tensile stresses. The team reportedly believes that their general approach, which involves the 3D printing of a metallic powder strengthened with ceramic nanowires, could be used to improve many other materials.
“There is always a significant need for the development of more capable materials for extreme environments. We believe that this method has great potential for other materials in the future,” said corresponding author, Ju Li, the Battelle Energy Alliance Professor in Nuclear Engineering, and a professor in MIT’s Department of Materials Science and Engineering (DMSE).
The team’s approach begins with Inconel 718, or alternative metal capable of withstanding extreme conditions such as temperatures of 700 degrees Celsius (approximately 1,300 degrees Fahrenheit). They then mill commercial Inconel 718 powders with a small number of ceramic nanowires, resulting in “the homogeneous decoration of nano-ceramics on the surfaces of Inconel particles,” according to the team. The resulting powder is used to create parts via laser powder bed fusion (LPBF).
The researchers found that parts made with their new powder have significantly less porosity and fewer cracks than parts made of Inconel 718 alone – leading to significantly stronger parts that also have several other advantages. For example, the parts are more ductile – or stretchable – and have much better resistance to radiation and high-temperature loading.
According to Li, the process itself is not expensive because “it works with existing 3D printing machines. Just use our powder and you get much better performance.”
“In this paper, the authors propose a new method for printing metal matrix composites of Inconel 718 reinforced by [ceramic] nanowires. The in-situ dissolution of the ceramic that is induced by the laser melting process has enhanced the thermal resistance and strength of Inconel 718. Moreover, the in-situ reinforcements reduced the grain size and got rid of flaws. Future 3D printing of metal alloys, including modification for high-reflectivity copper and fracture suppression for superalloys, can clearly benefit from this technique,” commented Xu Song, an assistant professor at the Chinese University of Hong Kong who was not involved in the work.
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