UCL researchers develop aluminum alloy purpose-built for DED printing

Researchers at University College London (UCL), working with colleagues at Brunel University London, have developed a bespoke aluminum alloy specifically for use in Directed Energy Deposition (DED) additive manufacturing.

The study, published in the International Journal of Extreme Manufacturing, reported that most aluminum alloys currently used in 3D printing were originally formulated for conventional casting, where metal cools slowly inside a mold. When subjected to the thermal extremes of DED, those standard materials frequently develop microscopic cracks or structural weaknesses.

“The current development of 3D printing focused mostly on printing process; high-quality printing part should start from the materials,” said the research authors, which include Prof. Peter D. Lee, Prof. Chu Lun Alex Leung, and Dr. Da Guo of UCL.

The team formulated a “hypereutectic” alloy composed of aluminum, nickel, cerium, manganese, and iron to test the theory. The material was engineered to solidify with a grain size of less than 5 micrometers — each grain containing an ultra-fine eutectic lattice structure below 200 nanometers.

With a freezing range of just 2.8°C, the alloy transitions from liquid to solid almost instantaneously, limiting the shrinkage that causes cracking in other high-strength materials.

When the alloy was tested against the widely used AlSi10Mg alloy under identical printing conditions, the new material produced components with 70% greater yield strength and 50% greater ultimate tensile strength.

Residual stress measured at less than 32 megapascals, which the authors described as negligible relative to the material’s overall strength.

The team also employed a “multimodal” observation method using synchrotron X-rays and infrared imaging to monitor temperature, crystal phase development, and stress accumulation in real-time during fabrication.