Jan 18, 2019 | By Cameron

In a collaborative study, researchers from Imperial College London and the University of Sheffield analyzed the lattice structures of 3D printed objects and compared them to the structure of a metallic single crystal. They found that the lattices follow metallurgical principles and replicate the monocrystalline structures of metals almost exactly, with the nodes of a 3D printed lattice equivocating to the atoms of a single crystal and the lattice struts serving as the atomic bonds.

In both structures, the atomic planes, or nodes in the case of the lattice, are all in alignment. That’s great for certain applications where it’s important to have resistance to deformation at extreme temperatures, such as jet engines. Such materials do have their drawbacks, though: when they are pushed to their breaking point, they fail catastrophically. That’s because a crack will always follow the path of least resistance, and in a monocrystalline material, that’s always a straight line because its nodes are the weakest points and the nodes are all aligned.

Polycrystalline materials, on the other hand, have many crystals and their atomic planes are randomly arranged. A crack in this material will be slowed by the path of least resistance winding in various directions between the nodes. So, if the internal lattices of 3D printed objects could be modeled after polycrystalline structures, those objects should theoretically be stronger.

And they are. The research team took models of polycrystalline atomic structures, scaled them up, and created mesostructures for 3D printing; they call these lattices meta-crystals. Their experiments revealed that the 3D printed objects with the polycrystalline lattices were up to seven times stronger than the standard lattice objects. That’s a significant strength difference for just rearranging some geometries, but only 3D printing could enable that discovery because literally no other method of fabrication can produce those structures.

Professor Iain Todd of the Department of Materials Science and Engineering at the University of Sheffield explained, “This approach to materials development has potentially far-reaching implications for the additive manufacturing sector. The fusion of physical metallurgy with architected meta-materials will allow engineers to create damage-tolerant architected materials with desired strength and toughness, while also improving the performance of architected materials in response to external loads.”

Dr. Minh-Son Pham of Imperial College London elaborated on the potential of combining the process with multi-material 3D printers, “This meta-crystal approach could be combined with recent advances in multi-material 3D printing to open up a new frontier of research in developing new advanced materials that are lightweight and mechanically robust, with the potential to advance future low carbon technologies." An example might be a helmet with a soft, rubbery exterior and a rigid, polycrystalline shell underneath, all 3D printed as a single object.



Posted in 3D Printing Materials



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