The oxidation of single-crystal nickel-based superalloys

Akhtar, A.; Hegde, Sathyapal; Reed, Roger C.

doi:10.1007/s11837-006-0066-0

Cited by 41 publications

(22 citation statements)

References 21 publications

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“…13 suggests the presence of an Al-rich precipitate with the ratio of atom% of Ni and Al approximately equal to unity suggesting the formation of the β (NiAl) phase. Similar oxidation induced phase transformation and formation of different Al-rich precipitates are reported in the oxidation studies of CMSX-10 by Akhtar et al [48]. The XRD patterns from the grip and the gauge region of the unpolished samples creep tested at 982…”

Section: Metallographic and Chemical Analysissupporting

confidence: 81%

Effect of Specimen Thickness on the Creep Response of a Ni-Based Single Crystal Superalloy (PREPRINT)

Srivastava¹,

Gopagoni²,

Needleman³

et al. 2012

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information AFRL-RX-WP-TP-2012-0394 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air Force Research Laboratory SPONSORING/MONITORING AGENCY ACRONYM(S)Materials SPONSORING/MONITORING AGENCY REPORT NUMBER(S) AFRL-RX-WP-TP-2012-0394 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. Preprint to be submitted to Acta Materialia. SUPPLEMENTARY NOTESThis work was funded in whole or in part by Department of the Air Force contract FA8650-08-C-5226. The U.S. Government has for itself and others acting on its behalf an unlimited, paid-up, nonexclusive, irrevocable worldwide license to use, modify, reproduce, release, perform, display, or disclose the work by or on behalf of the U.S. Government. PA Case Number and clearance date: 88ABW-2012-2171, 11 April 2012. This document contains color. ABSTRACTCreep tests on Ni-based single crystal superalloy sheet specimens typically show greater creep strain rates and/or reduced strain or time to creep rupture for thinner specimens than predicted by current theories which predict a size independent creep strain rate and creep rupture strain. This size dependent creep response is termed the thickness debit effect. To investigate the mechanism of the thickness debit effect, isothermal, constant nominal stress creep tests were performed on uncoated PWA1484 Ni-based single crystal superalloy sheet specimens of thicknesses 3.18mm and 0.51mm under two test conditions: 760•C/758MPa and 982•C/248MPa. The specimens contained initial micro-voids formed during the solidification and homogenization processes. The dependence of the creep response on specimen thickness differed under the two test conditions: at 760•C/758MPa there was a reduction in the creep strain and the time to rupture with decreasing section thickness while at 982•C/248MPa a decreased thickness resulted in an increased creep rate even at low strain levels and a decreased time to rupture but with no systematic dependence of the creep... SUBJECT TERMS AbstractCreep tests on Ni-based single crystal superalloy sheet specimens typically show greater creep strain rates and/or reduced strain or time to creep rupture for thinner specimens than predicted by current theories which predict a size independent creep strain rate and creep rupture strain. This size dependent creep response is termed the thickness debit effect. To investigate the mechanism of the thickness debit effect, isothermal, constant nominal stress creep tests were performed on uncoate...

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Section: Metallographic and Chemical Analysissupporting

confidence: 81%

Effect of Specimen Thickness on the Creep Response of a Ni-Based Single Crystal Superalloy (PREPRINT)

Srivastava¹,

Gopagoni²,

Needleman³

et al. 2012

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“…Company [44]. The microstructural stability in these alloys involved control of TCP phases that could precipitate in moderate amounts over a long time at temperatures above 900°C, but were detrimental to mechanical properties such as fatigue and creep resistance [45].…”

Section: Physical Metallurgy Of Single Crystal N5mentioning

confidence: 99%

Isothermal Oxidation Comparison of Three Ni-Based Superalloys

Mallikarjuna

Richards

Caley

2017

J. of Materi Eng and Perform

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“…The visual appearance, thickness, and oxide type is influenced by the material composition. Several oxidation studies of SRR99 [29,30] and CMSX10K (variant of CMSX10N) are available, [30][31][32] which provide good insight into the oxidation behavior of these materials. However, the key aspects to be emphasized is that these studies were performed under atmospheric conditions and for prolonged isothermal holds.…”

Section: Subsequent Oxidation Of Metal Surface Detached From Mold mentioning

confidence: 99%

“…This result is unlike in isothermal oxidation studies where the thickness of the oxide was of the order of 10 lm. [29][30][31][32] In fact, previous investigations into the oxidation of fully solutioned SRR99 over the temperature range of 1073 K to 1273 K (800°C to 1000°C) report the formation of an external layer of predominantly (Ni, Co) O with a small amount of (Ni, Co) TiO 3 , beneath which various internal spinel phases occur followed by internally oxidized chromium oxide and alumina, with Al 2 O 3 being the layer next to the unoxidized substrate. [30] The presence of the external predominantly (Ni, Co) O scale in that study differs from the observations reported in this investigation.…”

Section: Subsequent Oxidation Of Metal Surface Detached From Mold mentioning

confidence: 99%

Mechanism for Formation of Surface Scale during Directional Solidification of Ni-Base Superalloys

Brewster

D’Souza

Ryder

et al. 2011

Metall Mater Trans A

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Surface scale occurs on the external surface of directionally solidified, single-crystal turbine components. It is one of the most important casting defects because it affects the grain orientation assessment and causes incipient surface melting during heat treatment. The formation of surface scale comprises a three-stage process: (1) formation of a 0.5-to 1.5-lm Al 2 O 3 layer around the external surface of liquid metal as a result of the mold/metal reaction between the liquid and the mold prime coat; (2) separation of the solidified metal from the mold wall during cooling, where the Al 2 O 3 layer is stripped away from the metal surface but remains adhered to the mold; and (3) subsequent oxidation of the ''bare'' metal to form an oxide scale at the surface. The scale comprises a mixture of oxides. It is found that TiO 2 , Cr 2 O 3 , and Al 2 O 3 form on components cast using the 1st generation alloy, SRR99; however, in the case of castings using the 3rd-generation alloy, CMSX10N it is a predominately nickel-rich oxide (likely to be NiO). On the unscaled surface, the mold and metal are in intimate contact during casting, and subsequent cooling and the Al 2 O 3 layer around the external surface prevents subsequent oxidation of the casting surface.

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The oxidation of single-crystal nickel-based superalloys

Cited by 41 publications

References 21 publications

Effect of Specimen Thickness on the Creep Response of a Ni-Based Single Crystal Superalloy (PREPRINT)

Effect of Specimen Thickness on the Creep Response of a Ni-Based Single Crystal Superalloy (PREPRINT)

Isothermal Oxidation Comparison of Three Ni-Based Superalloys

Mechanism for Formation of Surface Scale during Directional Solidification of Ni-Base Superalloys

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