Carbides in NiCrMo system

Raghavan, M.; Mueller, R.R.; Klein, C.; Vaughn, G.A.

doi:10.1016/0036-9748(83)90281-8

Cited by 27 publications

(10 citation statements)

References 6 publications

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“…M 23 C 6 -type Carbide: These Cr-rich precipitates have a complex face-centered-cubic crystal structure with lattice parameter of over 10 angstrom [14,15]. In Ni-base alloys, these precipitates are found to contain Ni, Fe, Mo and some other elements from the matrix [8,14].…”

Section: Time -Temperature -Transformation (Ttt) Diagrammentioning

confidence: 99%

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Time-Temperature-Transformation Diagram of Alloy 945

Mannan¹

2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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Commercially produced INCOLOY ® alloy 945 was annealed and heat-treated in the temperature range of 650˚C to 982˚C for the times of 15 minutes to 100 hours. Heat-treated specimens were tested for hardness, optical metallography, scanning electron microscopy (SEM), energy dispersive x-ray (EDX) analysis of bulk and electrolytically extracted residue, x-ray diffraction (XRD) of the residue and transmission electron microscopy (TEM) to develop understanding for phase stability. Data generated from these analytical techniques is presented in the form of a time-temperature-transformation diagram (TTT).

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Section: Time -Temperature -Transformation (Ttt) Diagrammentioning

confidence: 99%

“…In Ni-base alloys, these precipitates are found to contain Ni, Fe, Mo and some other elements from the matrix [8,14]. In alloy 945 these are detected in the samples exposed for prolonged exposure of 50h at 649˚C and 25h at Eta Phase: Eta has a hexagonal DO 24 type structure [9,16].…”

Section: Time -Temperature -Transformation (Ttt) Diagrammentioning

confidence: 99%

Time-Temperature-Transformation Diagram of Alloy 945

Mannan¹

2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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“…The carbide particles obey a cube-to-cube orientation relationship with the austenite matrix. [23] have found that M 6 C-type carbides can dissolve significant amounts of nickel and chromium. Care was taken to select precipitates whose sizes were much larger than the electron probe diameter.…”

Section: B Postservice Microstructurementioning

confidence: 99%

Precipitation of an intermetallic phase with Pt2Mo-type structure in alloy 625

Sundararaman

Kumar

Prasad

et al. 1999

Metall Mater Trans A

131

102

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The microstructure of Alloy 625, which has undergone prolonged (ϳ 70,000 hours) service at temperatures close to but less than 600 ЊC, has been characterized by transmission electron microscopy. The precipitation of an intermetallic phase Ni 2 (Cr, Mo) with Pt 2 Mo-type structure has been observed in addition to that of the ␥" phase. Six variants of Ni 2 (Cr, Mo) precipitates have been found to occur in the austenite grains. These particles exhibit a snowflake-like morphology and are uniformly distributed in the matrix. They have been found to dissolve when the alloy is subjected to short heat treatments at 700 ЊC. The occurrence of the Ni 2 (Cr, Mo) phase has been discussed by taking the alloy chemistry into consideration. Apart from the intermetallic phases, the precipitation of a M 6 Ctype carbide phase within the matrix and the formation of near continuous films, comprising discrete M 6 C/M 23 C 6 carbide particles, at the austenite grain boundaries have been noticed in the alloy after prolonged service.

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“…However, EDS analysis could be used to differentiate between M,C and MZ3C6 type carbides. Raghavan et al [19] have observed that in M, C, chromium can substitute for molybdenum up to 30% while in M,,C, the solubility of molybdenum is only 10% in Ni-Cr-Mo alloys. Moreover, when the ratio of the concentration of chromium to that of molybdenum in the alloy exceeds 3, M,,C, nucleates predominantly; when this ratio is less than 3, M C type carbides precipitate [ 191.…”

Section: Nature Of Carbide Prechitatesmentioning

confidence: 99%

Carbide Precipitation in Nickel Base Superalloys 718 and 625 and Their Effect on Mechanical Properties

Sundararaman¹,

Mukhopadhyay²,

Banerjee³

1997

Superalloys 718, 625, 706 and Various Derivatives (1997)

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In addition to the precipitation of the strengthening intermetallic phases, namely, the metastable y" and y' phases, carbide phases also precipitate during age hardening heat treatments of Alloy 718 and Alloy 625. A detailed investigation has been carried out on the precipitation of primary and secondary carbide phases in these two alloys with reference to their identity, distribution and morphology. It has been found that the predominant carbide phase in Alloy 718 is a niobium rich MC phase, while in the case of Alloy 625, mainly M,,C, and, to some extent, M,C type carbides precipitate. Carbide precipitation during ageing has been seen to be confined almost exclusively to the austenite grain boundaries in both the alloys. NbC formation at the grain boundaries in Alloy 718 is associated with the appearance of distinct intermetallic precipitate ( y" and y' ) free zones near these boundaries whereas in Alloy 625, no well defined intermetallic precipitate free zones (PFZ) have been observed. The precipitation of different types of grain boundary carbides is discussed in terms of the differences in the chemistry of these alloys. The presence or absence of PFZ at grain boundaries is discussed in the light of solute depletion /vacancy depletion mechanisms.The influence of grain boundary carbide precipitation on the mechanical behaviour, especially the fracture mode, of these alloys has also been examined. It has been found that the progressive coverage of these boundaries with carbide particles results in a gradual transition in the fracture mode from transgranular to intergranular. Microcracks have often been found to nucleate at the matrix-carbide interface at the points of impingement of deformation bands.

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Carbides in NiCrMo system

Cited by 27 publications

References 6 publications

Time-Temperature-Transformation Diagram of Alloy 945

Time-Temperature-Transformation Diagram of Alloy 945

Precipitation of an intermetallic phase with Pt2Mo-type structure in alloy 625

Carbide Precipitation in Nickel Base Superalloys 718 and 625 and Their Effect on Mechanical Properties

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