Advancing Additive Manufacturing of Copper Alloys: Processing, Microstructure, and Property Optimisation

Abstract

Copper (Cu) and its alloys are indispensable to modern society due to their exceptional electrical and thermal conductivity, mechanical performance, and corrosion resistance. The transition towards Industry 4.0 and beyond has intensified demand for advanced Cu-based materials. Additive manufacturing (AM) offers the potential to realise these requirements through design flexibility, reduced material waste, and component customisation. However, its application to Cu alloys remains hindered by challenges intrinsic to Cu, such as high reflectivity and rapid heat dissipation. AM imposes cyclic, spatially localised energy inputs that generate steep thermal and stress transients, producing microstructural phenomena not predicted by steady-state metallurgy. Consequently, the fundamental links between powder feedstock, processing conditions, microstructural evolution, post-processing and the resulting mechanical and functional properties are not yet well understood, limiting the widespread adoption of AM Cu alloys.

This thesis systematically investigates how AM process parameters, alloying strategies, and powder feedstock characteristics govern the microstructure and performance of three representative Cu alloys—Cu-10Sn, Cu-1Ti, and Cu30Ni. Through a combination of advanced microscopy, mechanical and electrical testing, computational fluid dynamics simulations, thermodynamic simulations, and density functional theory calculations, this thesis establishes quantitative links between processing conditions, microstructural features, and macroscopic properties. Collectively, the findings provide new insights into the solidification pathways, microstructural evolution, and strengthening mechanisms unique to AM Cu-based alloys and deliver practical guidelines for optimising alloy and process design. By bridging fundamental metallurgy with AM-specific processing, the thesis contributes to enabling Cu alloys as next-generation functional and structural materials.