Degradation processes in high-temperature creep of cast cobalt-based superalloys

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68081723%3A_____%2F18%3A00492304" target="_blank" >RIV/68081723:_____/18:00492304 - isvavai.cz</a>

Alternative codes found

RIV/60193247:_____/18:N0000014

Result on the web

<a href="http://dx.doi.org/10.1016/j.matchar.2018.08.006" target="_blank" >http://dx.doi.org/10.1016/j.matchar.2018.08.006</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.matchar.2018.08.006" target="_blank" >10.1016/j.matchar.2018.08.006</a>

Result language

angličtina

Original language name

Degradation processes in high-temperature creep of cast cobalt-based superalloys

Original language description

Degradation processes in high-temperature creep of two cast high-chromium cobalt-based superalloys strengthened by niobium and tantalum for use in the glass industry were analysed via various experimental techniques. Constant load creep tests were conducted at 900, 950 and 1000 °C in a tensile stress range from 40 to 80 MPa. It was found that the CoNb superalloy possesses considerably longer creep life compared to the CoTa superalloy under the same loading conditions. Conversely, the creep ductility of the fractured specimens shows the opposite order of the creep life. The creep behaviour of both superalloys obeys the Monkman-Grant formula indicating that the creep deformation mechanism and fracture processes are mutually interlinked. The homogeneously distributed creep damage of the CoNb superalloy is closely connected with primary carbides and is predominantly initiated either as interface decohesion between the carbide/matrix and carbide eutectics/matrix or by breakage of bulk M23C6 carbides. The dominant type of creep damage in the CoTa superalloy is localized breakage of M23C6 carbides in close proximity of the fracture path. The final brittle fracture in the CoNb superalloy occurs via relatively fast propagation of the longest cracks after the ultimate state of damage is reached. Due to premature fracture, the inherent creep ductility of the CoNb matrix is not exhausted. The final ductile transgranular creep fracture of the CoTa superalloy is caused by a local strain-induced instability of the dislocation microstructure leading to a loss of an external section of specimen (necking).

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2018

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Materials Characterization

ISSN

1044-5803

e-ISSN

—

Volume of the periodical

144

Issue of the periodical within the volume

OCT

Country of publishing house

US - UNITED STATES

Number of pages

11

Pages from-to

479-489

UT code for WoS article

000447477300049

EID of the result in the Scopus database

2-s2.0-85051001566