Unweldable alloy makes connections with automotive industry

When the alloy is heated during welding, its molecular structure creates an uneven flow of its constituent elements - aluminium, zinc, magnesium and copper - which leads to cracks along the weld.

In an advance that could benefit the automotive industry, engineers at the UCLA Samueli School of Engineering have infused titanium carbide nanoparticles into AA 7075 welding wires, which are used as the filler material between the pieces being joined. A paper describing the advance was published in Nature Communications.

Using the new approach, the researchers are said to have produced welded joints with a tensile strength up to 392 megapascals. Post-welding heat treatments could further increase the strength of AA 7075 joints, up to 551 megapascals, which is comparable to steel.

AA 7075 can help increase a vehicle’s fuel and battery efficiency and it is already used to form plane fuselages and wings, where the material is generally joined by bolts or rivets. Similarly, the alloy has been used for products that don’t require joining, such as smartphone frames.