Impact of the Co/Ni-Ratio on Microstructure, Thermophysical Properties and Creep Performance of Multi-Component γ′-Strengthened Superalloys

Crystals

Steffen Neumeier¹  Carolin Zenk¹  PeterJ. Felfer¹  Nicklas Volz¹  ChristopherH. Zenk² 

[1] Department of Material Science and Engineering, Institute I, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Martensstr. 5a, 91058 Erlangen, Germany;Department of Material Science and Engineering, Institute II, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Martensstr. 5a, 91058 Erlangen, Germany;

关键词: cobalt;    nickel;    superalloy;    thermophysical properties;    segregation;    atom probe tomography;   

DOI  :  10.3390/cryst10111058

来源: DOAJ

【 摘 要 】

The Ni content is a crucial factor for the development of γ′-strengthened Co-based superalloys and some studies have systematically addressed its influence on various properties in model superalloys. In this paper, we report for the first time the influence of the Co/Ni ratio in the more advanced nine-component superalloy ERBOCo-1: exchanging Co and Ni in this Co/Ni-based superalloy while keeping the other alloying elements constants has a big influence on a variety of material properties. The elemental segregation after casting is slightly more pronounced in the alloy with higher Ni-content. Microstructural characterization of this alloy termed ERBOCo-1X after heat-treatment reveals that the precipitates are cuboidal in the Co- and spherical in the Ni-rich alloy, indicating a decrease in the γ/γ′ lattice misfit. Analyzing the elemental partitioning behavior by atom probe tomography suggests that the partitioning behavior of W is responsible for that. Furthermore, it is found that even though Ni exhibits the highest overall concentration, the γ matrix phase is still Co-based, because Ni is strongly enriched in the γ′ precipitates. Creep tests at 900 °C reveal that even though the microstructure looks less favorable, the creep resistance of the Ni-rich alloy is slightly superior to the Co-rich variant.

【 授权许可】

Unknown