Development of CuCrZr via Electron Beam Powder Bed Fusion (EB-PBF)

Abstract Precipitation hardened CuCrZr alloy is the baseline option as heat sink material for the water cooled W divertor concept of DEMO owing to its combination of high thermal conductivity and strength. However, traditional processing of CuCrZr by casting and forging or hot rolling involves several challenges: coarsening of Cr precipitates, microstructures highly heterogeneous, or difficulties in obtaining complex geometries. Additive Manufacturing (AM) enables creating innovative solutions with complex structures for heat exchangers and heat sinks. Compared to Laser Powder Bed Fusion (L-PBF), the EB-PBF (Electron Beam Powder Bed Fusion) AM technology offers advantages when processing copper alloys: it avoids difficulties associated to the high thermal conductivity and reflectivity of copper-based materials and prevents their oxidation by working under high vacuum. In this work the study of AM of a CuCrZr alloy with nominal composition 0.6–0.9 Cr, 0.07–0.15 Zr (wt.%) has been performed by EB-PBF. A detailed process parameters study has been performed to identify the process window and obtain dense materials free of defects. The process parameters, including post-built heat treatments like age hardening, were correlated with the microstructural evolution, the thermal conductivity and the hardness.