Strain-induced phase transformation in a cobalt-based superalloy during different loading modes

Benson, Michael L.; Liaw, Peter K.; Choo, Hahn; Brown, Donald W.; Daymond, Mark R.; Klarstrom, D. L.

doi:10.1016/j.msea.2011.03.096

Cited by 11 publications

(11 citation statements)

References 40 publications

(65 reference statements)

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“…Main reason for such a difference is the higher carbon content dissolved in the alloy studied in this investigation. On the other hand, elastic modulus values are in satisfactory agreement with those determined by other authors in cobaltbased superalloys [20] and nanostructured cobalt [21].…”

Section: Hardness and Elastic Modulus By Instrumented Indentation At supporting

confidence: 90%

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Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

Roa

Jiménez‐Piqué

Tarragó

et al. 2015

Materials Science and Engineering: A

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Section: Hardness and Elastic Modulus By Instrumented Indentation At supporting

confidence: 90%

“…Refs. [20,[28][29][30][31]), depending on stacking fault energy and/or loading mode. Attempting to get a more detail knowledge of the deformation scenario induced by nanoindentation, TEM lamellae were directly extracted by FIB from the center of residual imprints presented in Fig.…”

Section: Hardness and Elastic Modulus By Instrumented Indentation At mentioning

confidence: 99%

Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

Roa

Jiménez‐Piqué

Tarragó

et al. 2015

Materials Science and Engineering: A

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“…This suggests that a phase transformation from the FCC phase to HCP has occurred in the films, as the stacking sequences for HCP and FCC are close to each other . This phase transformation has been reported for CoCrFeNi and CoCrFeMnNi alloys. ,, Co has a stable HCP structure; as the films are composed of over 33 at % of Co, this could affect the phase transformation.…”

Section: Discussionsupporting

confidence: 63%

“…36 This phase transformation has been reported for CoCrFeNi and CoCrFeMnNi alloys. 36,47,48 Co has a stable HCP structure; 49 as the films are composed of over 33 at % of Co, this could affect the phase transformation.…”

Section: ■ Resultsmentioning

confidence: 99%

Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFe_xNi (0 ≤ x ≤ 0.7) Thin Films

Linder

Rao

Boyd

et al. 2022

ACS Appl. Energy Mater.

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Corrosion resistance and catalytic activity toward the oxygen reduction reaction (ORR) in an alkaline environment are two key properties for water recombination applications. In this work, CoCrFe x Ni (0 ≤ x ≤ 0.7) thin films were deposited by magnetron sputtering on polished steel substrates. The native passive layer was 2–4 nm thick and coherent to the columnar grains determined by transmission electron microscopy. The effect of Fe on the corrosion properties in 0.1 M NaCl and 1 M KOH and the catalytic activity of the films toward ORR were investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements indicate that CoCrFe0.7Ni and CoCrFe0.3Ni have the highest corrosion resistance of the studied films in NaCl and KOH, respectively. The high corrosion resistance of the CoCrFe0.7Ni film in NaCl was attributed to the smaller overall grain size, which leads to a more homogeneous film with a stronger passive layer. For CoCrFe0.3Ni in KOH, it was attributed to a lower Fe dissolution into the electrolyte and the build-up of a thick and protective hydroxide layer. Scanning Kelvin probe force microscopy showed no potential differences globally in any of the films, but locally, a potential gradient between the top of the columns and grain boundaries was observed. Corrosion of the films was likely initiated at the top of the columns where the potential was lowest. It was concluded that Fe is essential for the electrochemical activation of the surfaces and the catalytic activity toward ORR in an alkaline medium. The highest catalytic activity was recorded for high Fe-content films (x ≥ 0.5) and was attributed to the formation of platelet-like oxide particles on the film surface upon anodization. The study showed that the combination of corrosion resistance and catalytic activity toward ORR is possible for CoCrFe x Ni, making this material system a suitable candidate for water recombination in an alkaline environment.

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“…Özellikle yorulma direncini artırmak için tungsten karbür malzemelerin tane büyüklüklerinin artırılması tavsiye edilmektedir [15]. Kobalt ile üretilen sertmetallerde dikkat edilmesi gereken bir diğer konu da kobaltın sıcaklık ve deformasyon ile kristal yapı değişikliği yaşamasıdır [5,16]. Hegzagonal sıkı paket yapısına sahip allotropu göz önünde bulunduğunda, kobal malzemelerde içyapı ve kristal yapısına bağlı olarak kırılgan bir kırılma davranışı gözlenebilmektedir.…”

Section: Giriş (Introduction)unclassified

Fatigue Performance of Tungsten Carbide Cobalt (WC-Co) Hardmetals After Shot Peening

Toparli¹

2022

Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi

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Bu çalışmada, soğuk dövme kalıpları ve takım ucu gibi imalat sektörü açısından önemli alanlarda kullanılan tungsten karbür-kobalt (WC-Co) sertmetal malzemeler ele alınmıştır. İlgili metal-seramik kompozit malzemelerin yorulma ömrünün artırılması için özellikle havacılık ve otomotiv sanayinde kullanılan bilyalı dövme işlemi uygulanmıştır. Malzeme karakterizasyon testleri sonrası yorulma ömürleri elde edilmiştir. Yüzey pürüzlülük ölçümleri sonucunda, bilyalı dövme işlemi sonrası malzeme Ra ve Rz değerlerinde sırasıyla %113 ve %83’lük artışlar gözlenmiştir. Sertlik ölçümleri neticesinde, yüzeyde %13’lük bir artış olduğu ortaya çıkarılmıştır. Elde edilen derinlik profiline göre sertlik artışından etkilenen bölge derinliğinin yaklaşık 300 µm olduğu saptanmıştır. Yorulma testleri sonucunda bilyalı dövme işlemi sayesinde sertmetal numunelerin yorulma performansında iyileşme elde edilmiştir. Malzemedeki yorulma ömrü artışının bilyalı dövme sonucu elde edilen sertlik artışı sayesinde olduğu belirlenmiştir. Sertlik artışının plastik deformasyon sonucu gerinim sertleşmesi neticesinde olduğu ortaya konmuş, kobalt fazında herhangi bir kristal yapı değişikliği saptanmamıştır. Numunelerin kırılma yüzeyleri yorulma testleri sonrasında taramalı elektron mikroskobu ile incelenmiştir. Yorulma testi sonrasında gözlenen kırılmaların çoklu çatlak başlangıcı sonucu olduğu tespit edilmiştir. Tungsten karbür tanelerin hem bilyalı dövme hem de yorulma testi sonucunda kırıldığı gözlenmiştir. Kırılma esnasında hem tanelerarası hem de taneiçi çatlak ilerleme mekanizmalarının kırılmalara neden olduğu ortaya konmuştur. Ayrıca, incelenen kırılma yüzeylerinde sünek malzemelerde görülen yorulma yivciklerine rastlanmamıştır.

show abstract

Strain-induced phase transformation in a cobalt-based superalloy during different loading modes

Cited by 11 publications

References 40 publications

Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFe_xNi (0 ≤ x ≤ 0.7) Thin Films

Fatigue Performance of Tungsten Carbide Cobalt (WC-Co) Hardmetals After Shot Peening

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Strain-induced phase transformation in a cobalt-based superalloy during different loading modes

Cited by 11 publications

References 40 publications

Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFexNi (0 ≤ x ≤ 0.7) Thin Films

Fatigue Performance of Tungsten Carbide Cobalt (WC-Co) Hardmetals After Shot Peening

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Corrosion Resistance and Catalytic Activity toward the Oxygen Reduction Reaction of CoCrFe_xNi (0 ≤ x ≤ 0.7) Thin Films