Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys

Nickel and cobalt-based superalloys with a γ-γ' microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ' phase. In the present work the effe...

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Hoofdauteur: Ur Rehman, Hamad
Formaat: Online
Taal:Engels
Gepubliceerd in: FAU University Press 2025
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Online toegang:ONIX_20251215T160703_9783944057729_37
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author Ur Rehman, Hamad
author_browse Ur Rehman, Hamad
author_facet Ur Rehman, Hamad
author_sort Ur Rehman, Hamad
collection Directory of Open Access Books
description Nickel and cobalt-based superalloys with a γ-γ' microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ' phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W & Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.
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spelling doab-20.500.12854ir-1702612025-12-16T05:41:08Z Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys Ur Rehman, Hamad Kobaltbasierte Superlegierung Nickelbasierte Superlegierung Diffusion thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes Nickel and cobalt-based superalloys with a γ-γ' microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ' phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W & Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts. 2025-12-16T05:41:07Z 2025-12-16T05:41:07Z 2025-12-15T15:10:30Z 2016 book ONIX_20251215T160703_9783944057729_37 https://library.oapen.org/handle/20.500.12657/109206 9783944057729 9783944057712 https://directory.doabooks.org/handle/20.500.12854/170261 eng FAU Studien Materialwissenschaft und Werkstofftechnik open access image/jpeg n/a https://library.oapen.org/bitstream/20.500.12657/109206/1/9783944057729.pdf FAU University Press 2c600dea-eece-4066-87be-da335e323fdb 9783944057729 9783944057712 140 Erlangen open access
spellingShingle Kobaltbasierte Superlegierung
Nickelbasierte Superlegierung
Diffusion
thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes
Ur Rehman, Hamad
Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys
title Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys
title_full Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys
title_fullStr Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys
title_full_unstemmed Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys
title_short Solid Solution Strengthening and Difusion in Nickel- and Cobalt-based Superalloys
title_sort solid solution strengthening and difusion in nickel and cobalt based superalloys
topic Kobaltbasierte Superlegierung
Nickelbasierte Superlegierung
Diffusion
thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes
topic_facet Kobaltbasierte Superlegierung
Nickelbasierte Superlegierung
Diffusion
thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes
url ONIX_20251215T160703_9783944057729_37
work_keys_str_mv AT urrehmanhamad solidsolutionstrengtheninganddifusioninnickelandcobaltbasedsuperalloys