Metal 3D Printing Material Scalmalloy Could be the Aircraft Material of the Future

Aviation is one of the many industries around the world that’s increasing its adoption of 3D printing, which can be used to create the lightweight components and complex parts that are necessary for an airplane. The technology makes these parts with repeatable characteristics and consistently high quality, and can also decrease the amount of time, money, and materials needed to produce them, making the overall supply chain more efficient.

Speaking of these materials, we most often hear about components being made with strong thermoplastics and metals, such as titanium. But there’s another metal out there – a lightweight, corrosion-resistant aluminium alloy nearly as strong as titanium – that could be the hero we all need for the future of aircraft. I am of course referring to Scalmalloy, an aluminum-magnesium-scandium alloy developed and patented specifically for metal 3D printing by APWorks.

Scalmalloy is a highly ductile material that works on all existing powder bed SLM 3D printers. With a stable microstructure at temperatures of up to 250ºC, it’s highly weldable and can easily be machined for use in industries like aviation and automotive. Additionally, the material was developed specifically to use the lowest buy-to-fly ratio when compared to parts designed and manufactured using conventional methods.

Recently, a collaborative group of researchers from the Nanjing University of Aeronautics and Astronautics (NUAA) and the Fraunhofer Institute for Laser Technology (ILT) published a paper about another scandium-reinforced aluminum alloy, titled “Selective laser melting of rare earth element Sc modified aluminum alloy: Thermodynamics of precipitation behavior and its influence on mechanical properties,” in the Additive Manufacturing journal.

The abstract reads, “The interest of selective laser melting (SLM) Al-based alloys for lightweight applications, especially the rare earth element Sc modified Al-Mg alloy, is increasing. In this work, high-performance Al-Mg-Sc-Zr alloy was successfully fabricated by SLM. The phase identification, densification behavior, precipitate distribution and mechnical properties of the as-fabricated parts at a wide range of processing parameters were carefully characterized. Meanwhile, the evolution of nanoprecipitation behavior under various scan speeds is revealed and TEM analysis of precipitates shows that a small amount of spherical nanoprecipitates Al₃(Sc,Zr) were embedded at the bottom of the molten pool using a low scan speed. While no precipitates were found in the matrix using a relatively high scan speed due to the combined effects of the variation of Marangoni convection vector, ultrashort lifetime of liquid and the rapid cooling rate. An increased hardness and a reduced wear rate of 94 HV_0.2 and 1.74 × 10^-4 mm³N^-1 m^-1 were resultantly obtained respectively as a much lower scan speed was applied. A relationship between the processing parameters, the surface tension, the convection flow, the precipitation distribution and the resultant mechanical properties has been well established, demonstrating that the high-performance of SLM-processed Al-Mg-Sc-Zr alloy could be tailored by controlling the distribution of nanoprecipitates.”

The researchers fabricated Sc- and Zr-modified AI-Mg alloy using SLM 3D printing, and were then able to provide clarification on the relationships between the convection flow, precipitate distribution, mechanical properties, and scan speed. SEM and TEM characterize the various precipitation behavior between different scan speeds, and a relatively low scan speed helped to evaluate and explain how significantly the material’s hardness had improved.

Authors of the paper are Han Zhang, Dongdong Gu, Jiankai Yang, and Donghua Dai from NUAA, and Tong Zhao, Chen Hong, Andres Gasser, and Reinhart Poprawe from Fraunhofer ILT.

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[Images: APWorks unless otherwise noted]