Thursday , February 9 2023

Manufacture of additives reflects the fundamental metallurgical principles to create materials – ScienceDaily


Working in collaboration with colleagues at Imperial College London, Professor Iain Todd of the Department of Materials Science and Engineering at the University of Sheffield has taken a new approach to the development of engineering components produced by the manufacture of additives.

Manufacture of Additives (AM), also known as 3D printing, is often used to produce engineering components. Using lattice structures (such as those outlined below) to replace solid materials, these components are much lighter than their solid counterparts and can be designed to also show combinations of properties inaccessible to conventional solids. These structures are known as architectural materials.

These lattice structures typically have a uniform structure with nodes that match a common matrix with the bars between the nodes that follow all of the common planes: and here's the problem.

The paper, detailed in The nature on January 17, 2019, explains how these uniform sides replicate the structure of a metallic monocrystalline: AM nodes are equivalent to single crystal atoms and bars are equivalent to atomic bonds. In each of these structures, the atomic planes or nodes are perfectly aligned.

While in certain applications, such as the high temperature end of a jet engine, single crystal materials are ideal because of their ability to resist deformations at extreme temperatures, have limitations related to their mechanical performance. This limitation is also observed in AM parts with a uniform lattice structure.

When the structure is compressed, once the force is sufficient to cause permanent deformation, the lattice scissors along one or more node planes. With nothing to prevent this shear, the collapse becomes catastrophic.

In polycrystalline materials – those with many crystals – the alignment of atomic planes is random, when a shear force is in a certain direction, a crack will slow down or stop when a crystal is encountered where the atoms are aligned differently than the crystal in which triggered the crack. Moreover, it is possible to introduce different materials in the form of phases, precipitations or inclusions used to cure the materials; these materials also help to inhibit crack propagation.

This fundamental metallurgical understanding inspired scientists from the Imperial College of London and the University of Sheffield to mimic the polycrystalline microstructures on the AM side in order to develop robust, damaging, architectural materials.

By computerized modeling of atomic structures, their diminution, and the creation of meso-structures based on polycrystalline materials, engineers transform the way they design the materials for which the name "metacristals" was invented.

Experimental testing of components made from these methacrylates has shown that they are highly energy-absorbing and polycrystalline material able to withstand nearly seven times the energy before failure than materials that mimic the unique crystal structure.

While basic metallurgical concepts are used to inspire the development of architectural materials, researchers use the creation of architectural materials as an alternative approach to studying complex metallurgical phenomena.

Professor Iain Todd of the University of Sheffield: "This material development approach has potentially profound implications for the additive manufacturing industry. The merger of physical metallurgy with architectural meta-materials will allow engineers to create architecturally tolerant materials for damage with the desired power and hardness, while improving the performance of architectural materials in response to external tasks.

"And while these materials can be used as independent structures, they can be infiltrated with other materials to create composites for a wide variety of applications."

Dr. Minh-Son Pham of the Imperial College London: "This meta-crystalline approach could be combined with recent advances in 3D multi-material printing to open a new frontier of research into the development of new, lightweight and robust new materials from "Potential to Promote Future Low Carbon Technologies".

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