New titanium “metamaterial” has supernatural power

A new 3D printed ‘metamaterial’ that apparently has levels of strength/weight that appear to exceed those found in nature and most of the manufacturing world has been created by a team from RMIT University, Australia. This new material could have significant implications for everything from medical implants to aircraft and missiles.

The new metamaterial – an artificially structured material that exhibits electromagnetic properties not found in nature – is made from a common titanium alloy. But don’t let that fool you: there’s nothing common about its capabilities.

What makes the difference here is the structure. The material has a unique lattice design that not only makes it unique, but also extremely strong. According to the team’s new study, the material is 50 percent stronger than the next strongest alloy of comparable density, which is used in aerospace applications.

But how did they come up with this design? As with many groundbreaking inventions, the inspiration for this new material came from observations of the natural world. In this case, strong plants with sacred stems such as Victoria water lilies and hardy corals such as organ pipe coral (Tubipora music) offered instructions on how to combine lightness with durability.

But observing a strong natural structure is one thing, replicating it in artificial materials is another. For decades, researchers have tried to create their own hollow “cellular structures” similar to those found in nature’s examples, but their efforts have been frustrated by production problems and loading stress, leading to failures.

“Ideally, the stress should be uniformly distributed in all complex cellular materials,” Professor Ma Qian explained in a statement. “However, for most topologies it is common for less than half of the material to primarily carry the compressive load, while the larger material volume is structurally unimportant.”

However, what has made the difference in this case are the unprecedented innovative solutions that metal 3D printing offers.

“We have designed a hollow tubular lattice structure in which a thin belt runs. These two elements together show strength and lightness never before seen together in nature,” Qian added. “By effectively joining two complementary lattice structures to evenly distribute stress, we avoid the weak points where stress normally concentrates.”

Power but low cost

To create this new wonder material, Qian and colleagues 3D printed their design at RMIT’s Advanced Manufacturing Precinct using a technique called laser powder bed fusion. This approach fuses layers of metal powder together using powerful laser beams.

The result was a titanium lattice cube that is 50 percent stronger than the cast magnesium alloy WE54, the strongest alloy with a comparable density. This new structure effectively halved the amount of tension focused on the grid’s weak points.

The structure, a double-lattice design, also has the ability to deflect any cracks so that they do not undermine its toughness.

The structure can be scaled as needed, from something as small as a few millimeters to structures several meters in size, using different types of printers. Furthermore, the structure’s printability, biocompatibility, and corrosion and heat resistance make it a potential game changer for applications in various manufacturing areas.

“Compared to the strongest available cast magnesium alloy currently used in commercial applications requiring high strength and light weight, our titanium metamaterial of comparable density was found to be much stronger or less susceptible to permanent shape change under compressive loading, not to mention not to mention more feasibility. to produce,” explains lead author Jordan Noronha.

The team now plans to refine their material and explore its application in higher temperature environments. Currently the titanium cube can withstand temperatures up to 350°C (662°F), but they believe they can make it withstand temperatures up to 600°C (1,112°F). This would make it an excellent material for aerospace engineering and firefighting drones.

However, the technology needed to create the new material is not yet widely available, so its adoption may take some time.

“Traditional manufacturing processes are not practical for manufacturing these complex metal metamaterials, and not everyone has a laser powder bed fusion machine in their warehouse,” says Noronha.

“However, as the technology develops, it will become more accessible and the printing process will become much faster, allowing a wider audience to implement our powerful multi-topological metamaterials into their components. Importantly, metal 3D printing makes it easy to create net shapes for real-world applications.”

The article was published in the journal Advanced Materials.

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