High conductive copper alloys for additive manufacturing

Abstract

For applications where high thermal and/or electrical conductivity combined with reasonably high strength is required, copper alloys may be used. Although many different alloys were already developed in the past, additive manufacturing like laser powder bed fusion (PBF-LB/M) opens up new possibilities for alloy development, mainly driven by the very high cooling rates. This allows for the usage of precipitation-hardened alloys with compositions exceeding the maximum solubility. The present work focuses on the investigation of a well-known CuCr1Zr alloy as well as CuZr alloys with 1 and 2 wt.% Zr. For a fast, resource-efficient screening and demonstration of feasibility, the investigated alloys were not printed from powder. Instead, solid sheets were partially re-melted in a PBF-LB/M machine to obtain a microstructure similar to the printed state. This rapid-solidification microstructure is investigated, and precipitates with a size 50 nm or even smaller are found. After subsequent aging heat treatments, the hardness of the alloys exceeds the maximum hardness achievable with conventional manufacturing methods (excluding work hardening). The investigations in this work revealed the great hardening potential of these alloys for usage in the PBF-LB/M process.