Improving thermal conductivity of reduced-activation ferritic/martensitic steel using three-dimensional woven copper fiber

Reduced-activation ferritic/martensitic (RAFM) steel is a primary candidate for blanket modules in nuclearfusion reactors. Blanket modules transfer thermal energy generated by nuclear-fusion reactions to the coolant; therefore, blanket materials must have high thermal conductivity. RAFM steel is suitable for fusion reactors owing to its high strength, toughness, and resistance to neutron irradiation; however, its thermal conductivity is lower than that of other metals. This study fabricates RAFM steel-copper composites using three-dimensional (3D) woven copper fibers with different volume fractions as a preform to improve the thermal conductivity of RAFM steel around the coolant pipes. The microstructural, mechanical, and thermal properties of the developed composites and the correlations between them are experimentally investigated. Finite element simulations were also conducted on the composites comprising 3D woven copper fibers to evaluate the effective thermal conductivity. The factors that improve the effective thermal conductivity of RAFM steel-copper composites are discussed through a comparison with copper-powder composites with comparable volumes. This study demonstrates the manufacturing of composites with excellent thermal and mechanical properties using various 3D woven structures as preforms.