Laser Powder Bed Fusion processing of Invar 36® (Fe-36%Ni) for thermal expansion control in Space Satellite Components
In space, satellites are subject to extreme conditions with surface temperatures undergoing rapid and cyclical variation from -100°C to 120°C for some equipment, when in direct sunlight. Under these conditions materials with low thermal expansion are used to limit sensitive instrumentation from misalignment and to protect the structure from damage.
The binary alloy Fe-36%Ni also known as Invar 36® reaches an exceptionally low coefficient of thermal expansion of about 1 ppm/°K over a narrow compositional range thought to be related to sharp changes in magnetisation as well as a martensitic transformation from an fcc γ-phase to a bcc α-phase.
Laser powder bed fusion (LPBF) offers a number of benefits over traditional machining, allowing topologically optimised components with higher specific strength, a reduction in cost through payload weight reduction and less waste material during manufacturing, but also the potential of engineered hierarchical microstructures with controlled mechanical and thermal expansion properties.
The acceleration of the technology readiness of additive manufacturing of space components has been identified as a priority by the European Space Agency with challenges such as meeting quality requirements (repeatability and full data traceability of materials and designs through manufacturing steps from powder to part), establishing acceptable defects, qualification methodology, and standards and flight worthiness.
This presentation will summarise ongoing work commenced within the AMAZE project focussing on the increased understanding of the links between INVAR 36® powder characteristics and optimisation of thermal and mechanical properties over the narrow critical composition range of the alloy, specifically when processed by LPBF. Relatively large demonstrator satellite components for an optical spatial mechanism built for Thales-Alenia (France) will be available.
Professor Nicholas P Lavery’s research interests are largely defined by a varied career at the interface between industry and academia, evolving from a modelling background (degree in Mathematics/PhD in computational fluid dynamics) through to post-doctoral positions in engineering (simulation of manufacturing processes including powder compaction and casting). A transformative 5-year period as Exploitation Expert at the European Space Agency in Holland on the FP6 IMPRESS project (Intermetallic titanium aluminide alloys for aero-engines and nickel aluminide gas atomised powder for catalytic applications) propelled him into the area of materials engineering. During this period, he contributed to successfully funded FP7 proposals such as AMAZE (Additive Manufacturing for Zero Waste) and Accelerated Metallurgy (Rapid Alloy Prototyping).
On returning to Swansea University in 2013 and joining academic staff in the College of Engineering, he has focussed on materials research, setting up laboratories with state-of-the-art equipment such as the MACH1 centre for Advanced Materials Characterisation, with a £0.75M grant from the Welsh Government. Work in these labs has led to more recent grants such as the £1.4M COMET (Combinatorial Metallurgy) and £7M PROSPERITY EPSRC projects developing Rapid Alloy Prototyping methods.
In addition to this he leads the Additive Manufacturing Research Group, contributing to the AMAZE project until its completion in 2017 and successfully supervising post-graduates with companies such as Renishaw, Sandvik-Osprey, ESI Group and Qioptiq – often combining computational modelling, materials characterisation and alloy development, particularly for laser powder bed fusion.
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