New research work at the University of Lorraine into composite materials containing complex metallic alloys which feature quasicrystalline structure may be the gateway to stronger parts made with additive manufacturing technologies.
This new solution, meant to be used in SLS (selective laser sintering) printers, boasts properties superior to conventional alloys in that this new type of CMA incorporates quasicrystals to create mechanical properties like those of steel and brass, but at a much lower part density.
So what's a quasicrystal?
Most crystals have a three-dimensional arrangement of atoms which repeat in an orderly pattern, and depending on their chemical composition, have different symmetries. Imagine atoms arranged in repeating cubes. They have fourfold symmetry. Atoms in equilateral triangles have threefold symmetries. Quasicrystals, while they do have an orderly pattern which may be represented by shapes like pentagons, feature a pattern which never exactly repeats itself. They are, in fact, though they feature what is thought of as local symmetry, quite chaotic.
Daniel Shechtman won a Nobel prize for his work with them, and since his discovery, they've been found to have a single point in common. They tend to exist within two or three metal alloys. His discovery that quasicrystals feature a structure part crystalline and part disorganized means they're a hybrid of repeating, symmetric units and completely random blocks, and that was thought to be impossible.
The structure means, according to their research, that these materials are corrosion and wear resistant and feature low friction characteristics while offsetting the high density and brittle nature of many metal alloys.
The researchers, Samuel Kenzari, David Bonina, Jean Marie Dubois, and Vincent Fournée, say the quasicrystal materials – light-weight metal matrix composites – can be used to build 3D printed parts of a density lower by a factor of two and that polymer matrix composites reinforced by the crystal structure have been developed for both the direct SLS and SL technologies.
The Lorraine researchers' work demonstrates how the introduction of complex metallic alloys can be used as reinforcement particles in a polymer matrix. CMAs are basically compounds with large unit cells which might contain geometrical clusters of high symmetry.
The team says CMAs like quasicrystals will lead to the development of new composite materials adapted to additive manufacturing technologies. Standard CMA alloys are intrinsically brittle, and that prevents them from being used as bulk manufacturing materials, but the University of Lorraine team says the alternatives they've found involve using them as reinforcement particles or coating materials.
The researchers see applications for the technology in the automotive, aerospace and medical fields where part weight and density are at a premium.