Revealing bulk-like properties in freestanding PVD copper foils

Abstract

The discovery of novel metallic alloys with superior properties for structural applications is needed to address current challenges and enable technological advances. However, high-throughput fabrication of structural materials to explore a broad range of new chemistries is difficult using conventional bulk processing methods. Combinatorial sputter deposition of thin films is commonly used to rapidly explore wide compositional spaces for functional materials but typically produces fine-scale, columnar microstructures that differ from bulk counterparts and remain fixed to a substrate. Here, we demonstrate that a combination of sputter deposition, thermal annealing, and mechanical processing can be used to fabricate thick, free-standing foils with bulk-like microstructures for use in alloy design and discovery. To evaluate this concept, we selected pure copper as a model system, given its well-documented physical and mechanical properties and the extensive prior research available for meaningful comparison. Specifically, we sputter-deposit 200 μm thick Cu foils, remove them from their substrates for thermal and mechanical processing, and show that their mechanical and physical properties closely resemble those of conventionally processed bulk Cu foils.