Spacecraft operating in deep space environments are exposed to intense irradiation from solar energetic particles (SEP) and galactic cosmic radiation (GCR), dominated by protons, helium ions, and high-charge-and-energy (HZE) ions. These particles can induce irradiation-driven defect accumulation and microstructural evolution in structural alloys, including changes in precipitate stability that may affect mechanical performance. [1,2]

Aluminium alloys are widely used in space applications due to their high strength-to-weight ratio. AA2219 serves as a long-established baseline material for crewed pressure-vessel structures, while AA2195 has been implemented in selected spaceflight hardware to achieve mass savings through reduced density and improved specific strength and stiffness. [3] Beyond structural considerations, aluminium alloys are also of interest for radiation resistance, as their microstructure, particularly precipitate populations, can be tailored to enhance irradiation tolerance. T-phase-containing alloys, for example, have been reported to act as effective defect sinks. [4,5] However, irradiation of aluminium with highly energetic ions can generate secondary neutrons, posing risks to crew health and onboard electronics. Subsequent neutron capture and inelastic reactions may also produce gamma radiation, which must be considered in comprehensive shielding designs. [1,2]

This parameter study performs neutron and proton radiation transport calculations to systematically assess the radiation shielding performance of aluminium-based materials, with emphasis on secondary neutron generation, neutron attenuation, and neutron-induced photon radiation. The study addresses the central challenge in material selection for deep-space applications: balancing radiation protection against mass efficiency and mechanical performance. A broad range of aluminium alloys, metal-matrix composites, and multilayer material concepts is investigated to identify material- and geometry-dependent trade-offs between shielding effectiveness, secondary radiation production, and mechanical properties (e.g., specific strength). The results aim to clarify the compromises inherent in multifunctional shielding design and to support informed material selection for aluminium-based structural and shielding concepts.

References:

[1] M. Tunes; The Legacy and Future of Aluminum Alloys: Space Exploration and Extraterrestrial Settlement, ACS Materials Au, 2026.

[2] I. Jun et al.; A Review on Radiation Environment Pathways to Impacts: Radiation Effects, Relevant Empirical Environment Models, and Future Needs, Advances in Space Research, 2024.

[3] Light Metal Age Editorial Team; The Evolution of Constellium Al–Li Alloys for Space Launch and Crew Module Applications, Light Metal Age, online article, accessed 2026.

[4] M. A. Tunes et al.; Prototypic Lightweight Alloy Design for Stellar-Radiation Environments, Advanced Science, 2020.

[5] P. D. Willenshofer et al.; Radiation-Resistant Aluminium Alloy for Space Missions in the Extreme Environment of the Solar System, Advanced Materials, 2025.

Dipl.-Ing. Christoph Frühwirth