Materials that are critical to many important aerospace and energy applications must be able to withstand extreme conditions such as high temperatures and tensile stresses without failing. Now, a team of engineers at MIT Boston presents a simple, inexpensive way to strengthen one of the key materials used in such applications today.
The team believes that their general approach, which involves 3D printing of metallic powder reinforced with ceramic nanowires, can be used to enhance many other materials. “There is always a significant need to develop materials capable of operating in extreme conditions. We believe this method has great potential for other materials in the future,” says Ju Li, Battelle Energy Alliance Professor of Nuclear Engineering and Professor in the Department of Materials Science and Engineering at MIT (DMSE).
Li, who is also affiliated with the Materials Research Laboratory (MRL), is one of three authors of the paper, which was published in the journal Additive Manufacturing. Other authors include Professor Wen Chen of the University of Massachusetts at Amherst and Professor A. John Hart of the Department of Mechanical Engineering at MIT.
The team’s work began with the use of Inconel 718, a popular metal capable of withstanding extreme operating conditions such as temperatures up to 700°C. It has been milled with a small amount of ceramic nanowires, resulting in a “homogeneous nano-ceramic decoration on the surfaces of the Inconel particles.” The resulting powder is then used to create parts by 3D printing with a laser beam.
Researchers have found that parts made this way with the new powder have significantly less porosity and fewer cracks than parts made with Inconel 718 alone. This in turn leads to much stronger parts that also have a number of other advantages – for example, they are they have much better resistance to radiation and high temperature loads. Moreover, the process is not expensive as it works on existing 3D printing machines.
Li says the work “has the potential to open up a huge new space for alloy design,” as the cooling rate of ultra-thin layers of 3D-printed metal alloys is much faster than the rate for large parts created using conventional melting and solidification processes. As a result, “many of the chemical composition rules that apply to mass casting do not seem to apply to this type of 3D printing. Therefore, we have a much larger composition space to explore for the base metal with ceramic additives.”
Source: www.mit.edu