HRL Laboratories in California have made a metallurgical breakthrough; a technique to successfully 3D print high-strength aluminum alloys.

A new process for 3D printing aluminum alloys opens up the possibility for lighter, faster aircraft which could fly further using the same amount of fuel.

How so? Because modern planes are held together with thousands of metal rivets and fasteners; the lightweight but strong aluminum alloys used for the construction of their frames are impossible to weld.

If you were to try to weld them together, a phenomenon called hot-cracking would occur, where the finished alloy will weaken and fracture as it cools down.

But engineers at HRL Laboratories in Malibu, California, appear to have found a solution to this problem. They’ve developed a way to 3D print the two most commonly used types of high-strength aluminium alloys. And because melting and solidification in additive manufacturing is the same as welding, HRL’s nanoparticle functionalization technique can also make unweldable alloys weldable.

The implication is that these alloys can not only be used in aircraft, but also in the manufacture of cars and trucks. Furthermore, the team are investigating whether they can apply the same technique to 3D printing high-strength steels and nickel-based superalloys.

Aluminum Alloys Given Nano-Coating for 3D Printing

The breakthrough came about by coating the metal particles with specially selected nanoparticles. These work to seed and create a framework of the desired alloy microstructure as the laser-heated metal solidifies.

Whilst cooling, the molten alloy follows the crystalline pattern set by these nanoparticles, and prevents hot-cracking. That means the final, manufactured part retains its full physical strength.

To find suitable nanoparticles, the researchers sorted through the periodic table to select an element with the correct properties. Zirconium is relatively inexpensive, and in this case only makes up part of each particle, and is perfect for use in high-value applications.

Thus, the ability to weld aluminum aircraft should lead to significantly lighter aeroplanes. And when it comes to aviation, less weight means less money. A lighter frame allows aircraft to fly further on the same amount of fuel.

Source: HRL