The Role of Magnesium in Superalloys—A Review

Banerjee, Kumkum

doi:10.4236/msa.2011.29168

Cited by 4 publications

(7 citation statements)

References 23 publications

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“…Additionally, the Mg content in both samples (<80 ppm) is not sufficient to tie up the S (<250 ppm) (Table 1), as it has been previously prescribed that the concentration of Mg must be greater than or equal to that of S to facilitate segregation behavior in Ni-based alloys. [20,92] Thus, the S does not segregate, as there is no preferential gettering phase or element observed in the films without additions.…”

Section: Sputtering the Addition Of Tailorable Compositional Gettersmentioning

confidence: 99%

“…[19] To inhibit S embrittlement, reactive elements, such as Mg, can be added to Ni-based alloys in trace amounts to "tie up" the S before GB segregation and embrittlement occurs. [20] However, the high vapor pressure of Mg causes it to evaporate during AM processing, [21] thereby removing the barrier for S segregation. The effects caused by AM are emphasized in the work by Kassner et al which suggested that S embrittlement in AM Inconel alloys during high-temperature creep testing is attributed to 1) formation of Al 2 O 3 sites due to increased absorption of oxygen on the powder and 2) lack of a gettering element to tie up the S. As a result, the S preferentially segregated to the Al 2 O 3 sites, leading to secondary cracking and creep embrittlement.…”

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confidence: 99%

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Magnetron Sputtering as a Microstructural Screening Tool for Laser Additive Manufacturing: Study on Ni Superalloys

Goodelman,

Kassner,

Hodge

2024

Adv Eng Mater

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In this work, magnetron sputtering coupled with a heat treatment is demonstrated as a route to obtain surrogate microstructures comparable to those achieved by laser‐based additive manufacturing (AM) for Ni‐superalloys. Furthermore, this technique is shown to be a novel and efficient way of screening elemental additions with high compositional resolution for AM, without the need for designing and characterizing custom atomized powders. Here, Inconel 718 films are sputtered from both arc melted and AM targets to capture any compositional changes and to develop a comprehensive methodology. Films were characterized via electron microscopy techniques to establish similarities between sputtered plus heat‐treated films and bulk AM Inconel 718 microstructures reported in literature. Since Inconel 718 is susceptible to high temperature S embrittlement, films were then co‐sputtered with small amounts of Zr or Hf, which were found to facilitate sulfur segregation via NanoSIMS analysis. Overall, this work highlights how magnetron sputtering plus heat treatment can be leveraged to rapidly screen novel AM microstructures, thereby accelerating the development and deployment of AM materials.This article is protected by copyright. All rights reserved.

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Section: Sputtering the Addition Of Tailorable Compositional Gettersmentioning

confidence: 99%

mentioning

confidence: 99%

Magnetron Sputtering as a Microstructural Screening Tool for Laser Additive Manufacturing: Study on Ni Superalloys

Goodelman,

Kassner,

Hodge

2024

Adv Eng Mater

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“…These types of carbides react with oxygen and therefore have the potential to locally disrupt the formation of the protective scale [16,17]. In addition, the carbides may provide shortcircuit diffusion paths either: through the dislocation arrays at the interface with the matrix [21], or by differences in thermal expansion properties [15] which may cause micro-cracking at the interface with the matrix during thermal cycling. Hence, surface-connected refractory metal carbides may shorten or negate the incubation period in localised regions at the surface of the superalloy [16].…”

Section: Introductionmentioning

confidence: 99%

Surface Roughness Evolution to Identify Incubation Time for Hot Corrosion of Nickel-Base Superalloys: CMSX-4, CM247LC DS and IN6203DS at 550 °C

et al. 2020

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In the absence of protective scales, nickel-base superalloys have an extremely limited hot corrosion incubation period before increased rates of attack are experienced. This paper reports on the nickel-base superalloys: CMSX-4, CM247LC DS and IN6203DS subjected to 550 °C hot corrosion exposures of durations ranging from 0 to 800 h, during which none of the superalloys developed a fully protective scale. The aim of the research was to identify the incubation period of each superalloy and this was achieved by means of surface roughness evaluations. A metrology exercise was performed on the cross section of test specimens which produced Cartesian data points which were subsequently converted to Ra and Rz data. Statistical analysis of the results suggested the incubation period lasted approximately 400, 500 and 200 h, respectively, for each superalloy. It was concluded that refractory metal phases within the microstructure were associated with the relatively short IN6203DS incubation period. This paper demonstrates that monitoring the changes in surface roughness provides a plausible method to identify the transition from incubation to propagation when studying 550 °C hot corrosion attack.

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“…It is well known that the addition of microalloying elements such as magnesium, calcium and boron has a strong influence on the mechanical properties of both wrought and cast nickel-base superalloys [1][2][3]. Moreover, the addition of 194 ppm by mass magnesium in nickel-base and iron-nickel-base superalloys has been shown to improve properties such as stress rupture life and creep life, a function currently fulfilled by cobalt, which is a critical element and is the subject of a drive to reduce its use [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…However, the addition of more than 400 ppm magnesium can lead to the formation of Ni 2 Mg, a brittle phase, which deteriorates hot workability but may benefit forgeability [12]. Previous investigations consistently state that a small amount addition of magnesium in nickel-base and iron-nickel alloys can improve creep and stress rupture properties due to the spheroidization of precipitates [1][2][3][4][5][6][7][8][9][10][11][12]. Moreover, the stress required for plastic deformation can be increased by an addition of magnesium due to substitutional solid solution strengthening and causing an increase in dislocation density, prolonging work hardening [13].…”

Section: Introductionmentioning

confidence: 99%

Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation

Al-Saadi

Hulme-Smith

et al. 2020

Metals

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Alloy 825 is widely used in several industries, but its useful service life is limited by both mechanical properties and corrosion resistance. The current work explores the effect of the addition of magnesium on the recrystallization and mechanical behavior of alloy 825 under hot compression. Compression tests were performed under conditions representative of typical forming processes: temperatures between 1100 and 1250 °C and at strain rates of 0.1–10 s−1 to a true strain of 0.7. Microstructural evolution was characterized by electron backscattered diffraction. Dynamic recrystallization was found to be more prevalent under all test conditions in samples containing magnesium, but not in all cases of conventional alloy 825. The texture direction ⟨101⟩ was the dominant orientation parallel to the longitudinal direction of casting (also the direction in which the samples were compressed) in samples that contained magnesium under all test conditions, but not in any sample that did not contain magnesium. For all deformation conditions, the peak stress was approximately 10% lower in material with the addition of magnesium. Furthermore, the differences in the peak strain between different temperatures are approximately 85% smaller if magnesium is present. The average activation energy for hot deformation was calculated to be 430 kJ mol−1 with the addition of magnesium and 450 kJ mol−1 without magnesium. The average size of dynamically recrystallized grains in both alloys showed a power law relation with the Zener–Hollomon parameter, DD~Z−n, and the exponent of value, n, is found to be 0.12. These results can be used to design optimized compositions and thermomechanical treatments of alloy 825 to maximize the useful service life under current service conditions. No experiments were conducted to investigate the effects of such changes on the service life and such experiments should now be performed.

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The Role of Magnesium in Superalloys—A Review

Abstract: The role of magnesium (Mg)

Cited by 4 publications

References 23 publications

Magnetron Sputtering as a Microstructural Screening Tool for Laser Additive Manufacturing: Study on Ni Superalloys

Magnetron Sputtering as a Microstructural Screening Tool for Laser Additive Manufacturing: Study on Ni Superalloys

Surface Roughness Evolution to Identify Incubation Time for Hot Corrosion of Nickel-Base Superalloys: CMSX-4, CM247LC DS and IN6203DS at 550 °C

Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation

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