Load-bearing components in the aerospace industry, such as engine mounts and landing gear, are subject to repetitive stress cycles which can lead to the formation of micro-cracks. In conventional materials, these micro-cracks propagate and can eventually lead to the fracture of the component. Self-healing alloys form a class of materials that deal with stress cycles by undergoing a phase transformation which allows the material to absorb the strain created in the materials. Only a limited number of alloys are known to exhibit this behaviour and there is a requirement to broaden the selection of alloys with diverse mechanical properties, to allow their use in a wider range of components. Further, a knowledge gap exists between the two manufacturing methods used for these components, which require a high level of precision.
In September 2015, Ilika announced that Innovate UK, the UK grant body, had awarded it the lead role in a £2.15 million, 3-year collaborative project to develop novel self-healing alloys with GKN Aerospace Services, BAE Systems, Reliance Precision Engineering and the University of Sheffield. The project takes a fully integrated approach to developing the alloys, starting with high throughput synthesis and screening of candidate materials. A shortlist of those materials exhibiting the correct phase transformations are made as powders suitable for additive manufacturing (AM). Key aerospace components which are known to be subject to stress cycling are being made using a unique combination of AM and precision subtractive manufacturing. This is paving the way for the manufacture of components with critical feature tolerances designed to be of lower weight but with both structural integrity and functional performance.