Analyzing the Precipitation Effects in Low-Alloyed Copper Alloys Containing Hafnium and Chromium
Julia Dölling,
Moritz Kuglstatter,
Ulrich Prahl,
Heinz Werner Höppel,
Patrick Ortner,
Benedict Ott,
Stefanie Felicia Kracun,
Martin Fehlbier,
Andreas Zilly
Affiliations
Julia Dölling
Faculty of Technology, Cooperative State University Stuttgart, Lerchenstr. 1, 70174 Stuttgart, Germany
Moritz Kuglstatter
Department of Materials Science & Engineering, Institute I: General Materials Properties, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 5, 91058 Erlangen, Germany
Ulrich Prahl
Institute of Metal Forming, TU Bergakademie Freiberg, Bernhard-von-Cotta-Str. 4, 09599 Freiberg, Germany
Heinz Werner Höppel
Department of Materials Science & Engineering, Institute I: General Materials Properties, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 5, 91058 Erlangen, Germany
Patrick Ortner
Department of Materials Science & Engineering, Institute I: General Materials Properties, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 5, 91058 Erlangen, Germany
Benedict Ott
Department of Materials Science & Engineering, Institute I: General Materials Properties, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 5, 91058 Erlangen, Germany
Stefanie Felicia Kracun
Department for Casting-Technology (GTK), University Kassel, Kurt-Wolters-Str. 3, 34125 Kassel, Germany
Martin Fehlbier
Department for Casting-Technology (GTK), University Kassel, Kurt-Wolters-Str. 3, 34125 Kassel, Germany
Andreas Zilly
Faculty of Technology, Cooperative State University Stuttgart, Lerchenstr. 1, 70174 Stuttgart, Germany
Copper alloys containing chromium and hafnium combine elevated mechanical strength and high electrical and thermal conductivity. For the simultaneous enhancement of both material properties, precipitation hardening is the utilized mechanism. Therefore, the aim is to analyze the influence of chromium and hafnium in binary and ternary low-alloyed copper alloys and to compare the precipitation processes during temperature exposure. Atom probe tomography (APT) and differential scanning calorimetry (DSC) measurements enable to understand the precipitation sequence in detail. CuCr0.7 starts to precipitate directly, whereas CuHf0.7 is highly influenced by prior diffusion facilitating cold rolling. Within the ternary alloy, hafnium atoms accumulate at the shell of mainly Cr-containing precipitates. Increasing the local hafnium concentration results in the formation of intermetallic CuHf precipitates at the sites of mainly Cr-containing precipitates. Indirect methods are utilized to investigate the materials’ properties and show the impact of cold rolling prior to an aging treatment on binary alloys CuCr and CuHf. Finally, ternary alloys combine the benefits of facilitated precipitation processes and decelerated growing and coarsening, which classifies the alloys to be applicable for usage at elevated temperatures.
