Titanium carbide makes aluminum alloy viable for cars

Two pieces of aluminum alloy 7075 welded together using a nanoparticle-enhanced filler wire. Photo by Oszie Tarula, UCLA.

Engineers from UCLA have developed a way to make an aluminum alloy known as AA 7075 so strong that it can be welded without breaking.

In a paper published in Nature Communications, the researchers explain that they achieved such result by infusing titanium carbide nanoparticles into AA 7075 welding wires, which are used as the filler material between the pieces being joined.

First discovered in the 1980s in what is now Kyrgyzstan, titanium carbide occurs in nature as a form of the very rare mineral khamrabaevite or Ti,V,Fe.

According to the UCLA engineers, AA7075 was developed in the 1940s and has long held promise for use in automobile manufacturing because it is nearly as strong as steel and has just one-third of the weight. However, it is almost impossible to weld together using the technique commonly used to assemble body panels or engine parts because when it is heated, its molecular structure creates an uneven flow of its constituent elements — aluminum, zinc, magnesium and copper — which results in cracks along the weld.

But using the new approach, the researchers produced welded joints with a tensile strength up to 392 megapascals. In a press release, they said that, by comparison, an aluminum alloy known as AA 6061 that is widely used in aircraft and automobile parts, has a tensile strength of 186 megapascals in welded joints.

In addition to the method they employed, the experts say that if post-welding heat treatments are also applied, AA 7075 joints could see an increase in their strength of up to 551 megapascals, which is comparable to steel.

“The new technique is just a simple twist, but it could allow widespread use of this high-strength aluminum alloy in mass-produced products like cars or bicycles, where parts are often assembled together,” said Xiaochun Li, the study’s principal investigator, in the media statement. “Companies could use the same processes and equipment they already have to incorporate this super-strong aluminum alloy into their manufacturing processes, and their products could be lighter and more energy efficient, while still retaining their strength.”