Metal Information Center

Aerospace wary of aluminum-lithium: but producers, anticipating growth, are stepping up production - aluminum-lithium alloys

December 22, 2007 – 6:57 am

Boeing is working with an aluminum-lithium alloy developed by Inco Ltd., according to Edward Burrell, vice president of marketing for Inco. Called AL-905XL, it can be used in landing gear, aircraft wheels and even seat supports.

Textron Aerostructures, which builds wing structures for the B-1B, the L-1011 and recently won contracts for the upcoming Airbus A-330/340, also is experimenting with aluminum-lithium in this area, said Topper Long, the division’s vice president of marketing. None of this work is for immediate commercial application, however.

“We’re looking at it. We’ve done a lot of work on it, including work with Alcoa,” he said.

Textron Aerostructures has done chemical etching of aluminum-lithium parts, although Long admitted “there’s still a long way to go.” The advantages are that chemical etching offers labor and thus cost savings. “There are a lot of pros and cons to it–just as there are to chemical etching of aluminum parts,” he said.

One of the major problems with the alloy is its lack of transverse strength. Earlier this year British Aerospace engineers said the alloy was not considered for initial production of the A-330/340 aircraft because of this failure. The decision to switch to aluminum-lithium implies greater confidence in the alloy’s strength.

Inco executives at the fair said they have achieved a high dispersive strength in the alloy that prevents transverse weakness. In forgings, a uniform structure is achieved that does not require heat-treatment or cold deformation.

Inco, meanwhile, has invested $4.75 million to increase output of aluminum-lithium alloys at a plant in Pittsboro, N.C., expanding on developement work in the past in Wyckoff, N.J. So far, Inco has sold a similar alloy, aluminum-magnesium, for a torpedo hull.

Also, there are signs the alloy could be used in the engine for the European Fighter Aircraft, backed by a consortium of European nations, and the Rafale, to be built by France, according to aluminum producers.

The major consumption of aluminum-lithium will be in sheet products in the wing, but this is still down the road, according to executives at Pechiney of France. “The largest use will be in damage-tolerant sheet in the aircraft skin for commercial uses. Its stiffness and density could be used for maximum effect,” said a Pechiney executive at the show.