Back in the frame

The use of aluminium alloys in aircraft is growing thanks to a new, lighter composition and the ease with which they are recycled. Berenice Baker reports

Technical innovation and environmental factors are boosting the credentials of aluminium alloys as a long-term option for the aerospace industry, claims one of the world’s major suppliers of the materials.

Alcan Global Aerospace Transportation and Industry (ATI), which provides aluminium alloys used in the airframes of commercial aircraft, said new forms are leading a resurgence in demand thanks to their light weight, durability and ability to be recycled.

The company used this month’s Paris Air Show as a platform to stake aluminium’s claim in the future of aerospace materials, where innovations in composites have attracted most attention in recent years.

Christophe Villemin, president of Alcan Global Aerospace, said: ‘Something we want to highlight in current economic conditions is that aluminium is a proven and safe solution in terms of manufacturing for aerospace companies. We are able to respond to cost and technological challenges and we want to show that there is still a strong innovation potential for those materials.’

Alcan Global Aerospace has factories in Europe and the US, producing plate, rolled or extruded products, some of which are pre-machined or welded for customers. The company makes products for OEMs such as Airbus or Boeing, Tier 1 suppliers or sub-contractors.

Tim Warner, from Global ATI’s research-and-development (R&D) centre, said: ‘One of the key elements to recent use of aluminium is the addition of lithium, which reduces the density of the alloys and makes them even lighter. We’ve also been working on understanding the balance between the alloy additions — copper, lithium and silver in particular — in order to achieve a balance of strength, damage control and stability properties for the airframe business.’

Alcan is attempting to carve out a niche as a key player in the recycling business, working on ways to recycle aluminium throughout the logistic chain as well as at the end of an aircraft’s life. It believes 100 per cent of the aluminium processed in the logistic chain — at Alcan’s plants, by contractors and by OEMs — could be taken back and reprocessed.

When an aircraft reaches the end of its flying years its fate is entirely dependent on the choice of materials. Alcan is working with Airbus on the PAMELA project to test the end-of-life recycling of an aircraft, segregating its component parts and taking the aluminium back into its plant for remelting and recasting.

New joining technology is another area in which the aluminium industry hopes innovation can boost its fortunes. ‘For the last 50 years or so, joining technology has been the same: riveting,’ added Warner. ‘Now more recent planes, for instance the A380, have been using welding, particularly laser beam and friction stir welding. These are very attractive technologies in terms of cost and overall performance capabilities. Other technologies, such as adhesive bonding as a replacement for fastening and riveting technologies, are moving quickly.’

Alcan also worked on the Ariane 5 programme, providing parts for the engine boosters. ‘The space industry is exciting for us, stimulating in terms of the R&D needed to survive extremely demanding environments,’ explained Villemin. ‘Though it is a small market, we can also transfer these technologies to more commercial applications.’

According to Alcan, the key current and future trends for materials in the aerospace industry are continued light-weighting, cost effectiveness and recycling. Another influential issue is making assemblies from different materials and the challenges this raises in terms of, for instance, joining aluminium alloys to carbon fibre reinforced plastics (CFRP) to support the future hybrid-material world. Smart materials, which monitor the properties and the behaviour of material, in real time, will also appear in aircraft in the near future, it said.