Rethinking Cu-Cr Electrical Contact Microstructures: From Manufacturing to Properties

Cu-Cr based alloys with Cr content ranging from 20 to 50 wt. % are extensively explored for thermo-electrical applications, especially in the case of electrical contacts in vacuum interrupters for medium voltage applications, because of their excellent combination of electrical, thermal, and mechanical properties. These properties result from a good electrical conductor material, Cu, and a semi-refractory metal, Cr. Different manufacturing techniques are used to manufacture these binary alloys, solid-state sintering (SSS), and vacuum-arc remelting (VAR) being among the most widely used industrially. The resulting microstructures are mainly driven by the process itself and consequently constrained to the limits imposed by their conventional manufacturing processes. In this study, we propose a different approach to rethink the microstructure, and thus, the properties of Cu-25Cr composites for medium voltage electrical contacts. Using a rapid solidification manufacturing technique, such as powder bed fusion additive manufacturing, we show that the microstructure can be drastically changed, as for Cr-phase size and morphology. The evolution of electrical, thermal, and mechanical properties of such microstructures is also characterized and discussed. We highlight the microstructure-properties relationship of these new microstructures for enhancing electrical contact's performances compared to the conventional Cu-Cr materials.