3D-printed LIGhtweight architected materials for High-Temperatures (3D-LIGHT)

Weight is at a premium for aerospace applications. Innovations have been driven to reduce the weight of engines for fuel saving, such as Rolls-Royce’s honeycomb fan blade and GE’s composite fan case. A jet engine is made of one tonne of high-density heat-resistant superalloys. However, they are necessary because higher temperatures give higher thermal efficiencies in propulsion. This research aims to produce lightweight high-temperature structures by introducing porosity to non-critical load-bearing parts thus reducing their relative density. Given the importance of lightweighting, it might even be possible to make them float. Hollow superalloys exist, but they are not intricate and limited by casting precision, the finest cavities are a few millimetres requiring extensive chemical leaching afterwards. Fortunately, recent ground-breaking developments in 3D-printing make crack-resistant superalloys manufacturable from powder of a diameter less than that of human hair. Thus far, research on metal 3D-printing has heavily concentrated on consolidating powder to 100% density. Yet, porous materials can be adopted with cellular (cavity) sizes more than ten times finer than casting. Each cell is a building block, it has struts or surfaces that can be designed to deform under stretch, bend or shear mode. Thus, enabling the engineering of microscopic cellular structures, we can manipulate their macroscopic behaviour. This class of materials is known as architected materials, widely researched, but only at room temperature. Understandably hindered by available heat-resistant materials. But the deformation behaviour and mechanical properties – particularly in extreme environments – need to be proven and it is aimed to do this here. This research will leverage the advances in superalloys 3D-printing and architected materials – a new interdisciplinary subject. We will concentrate on using new generations of printable superalloys designed specifically for 3D-printing. My preliminary results, for example on the architected superalloy ABD-900AM, have illustrated unexpected embrittlement and pronounced asymmetry in micro- and macroscopic mechanical behaviour at high temperatures, attributed to operative damaging routes. By understanding their mechanisms, we can possibly decode unnatural behaviours as seen in the room temperature counterparts, such as tuneable thermal expansion or ultra-damage tolerance. The proposed work will determine the causality by studying microscopic deformation modes under hinging and buckling as well as accounting for various damage mechanisms including plasticity, creep relaxation and oxidation. Necessary new knowledge must be generated to better manipulate the distribution and orientations of the constitutive structural units, so they are mechanical sound at elevated temperatures. This work is comprised of cohesive work packages spanning design, manufacture, testing and modelling. We have two major goals: (1) to understand the deformation and fracture of architected materials with experimental evidence from loading under extreme conditions and (2) to create high fidelity models (focusing on finite element based) that accurately describe and predict their behaviour. We will initially focus on idealised simple structures (honeycomb and truss-lattices) and then extend to stochastic structures with non-repeating units (Voronoi). This work will emphasise the effect of work hardening/softening, strain-rate sensitivity and influence of oxidation. This work will help the UK to increase its competitiveness in the booming 3D-printing market which is estimated to be £15bn. The sector has played an increasingly important role in recent years in derisking supply chain issues via localised materials supply, logistics and manufacturing. It would also reinforce the UK’s global leadership in several high-tech sectors such as aerospace, satellites and orthopaedics.