An image of the printed meta-crystalCreating a new family of materials: meta-crystals

Equipment from Royce@Sheffield has been instrumental in creating a new family of materials. Meta-crystals have taken inspiration from naturally occurring polycrystalline materials to create non-uniform lattices with much more mechanical strength than a uniform lattice structure. The meta-crystals were printed on Royce@Sheffield’s Arcam Q20+, an industrial-grade machine that builds fully dense metal components using a high power electron beam, supported by a vacuum environment and high temperatures.

While uniform lattice structures - which replicate the structure of a metallic crystal – are ideal for some applications, when compressed the lattices shear, leading to a catastrophic collapse. Taking instead a computer model of the atomic structure of a polycrystalline material means that meta-crystals have a more random alignment. This means that a crack created by a shear force in any particular direction is slowed down or stopped when it meets a crystal where the atoms are aligned differently to the first. Even more exciting is the prospect that with additive manufacturing it will be possible to introduce different materials throughout the structure, further inhibiting crack propagation.

Experimental testing of components made from these meta-crystals has demonstrated that they are highly energy absorbent. Compared with the single-crystal structure lattice materials, the poly-crystal-like material able to withstand almost seven times the energy before failure.

Scientists at Imperial College London and The University of Sheffield collaborated on this study, the initial results of which were published in Nature in January (Vol 565, Issue 7739, 17 January 2019).

Director of the Royce Translational Centre Professor Iain Todd said: “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.

“And while these materials can be used as standalone structures, they can also be infiltrated with other materials in order to create composites for a wide variety of applications.”

Dr Minh-Son Pham of Imperial College London: “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."

To discuss using the Arcam Q20+, please contact Royce@Sheffield: royce@sheffield.ac.uk