Directional recrystallization of ODS alloys by means of zone annealing

Sugino, Yoshito; Ukai, Shigeharu; Hayashi, Shigenari; Tang, Qingxin; Leng, Bin

doi:10.1016/j.jnucmat.2011.01.062

Cited by 14 publications

(14 citation statements)

References 7 publications

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“…Note that the temperature gradient along the drawing direction depends on the experimental set-up used for directional recrystallisation. Usually, the temperature gradient of air-cooled furnaces is tens to several hundreds of K cm −1 [7][8][9]15,26,35,36,45,47,57] while furnaces designed with a heat sink can provide a temperature gradient from 100 to 1000 K cm −1 [3][4][5][6]8,[35][36][37][38][39][40][41][42][43][44]46,48,49,52,53,55,56], depending on the furnace layout and cooling system. The heating source, cooling method and temperature gradient noted in various papers are listed in Table 2.…”

Section: Temperature Gradientmentioning

confidence: 99%

“…The heating source, cooling method and temperature gradient noted in various papers are listed in Table 2. For furnaces where the heating unit moves when the sample is static [6,18,[20][21][22][23]25,28,30,31,33,35,50], the temperature gradient often changes continuously during processing since the distance between the heating unit and heat sink changes; while for furnaces where the sample travels when the heating unit is static [8,[35][36][37][38][39][40][41][43][44][45][46]48,49,[52][53][54][55][56][57][58], the temperature gradient is usually constant as long as the sample is long enough. It is clear that static heating unit design is better for directional recrystallisation research since the temperature gradient is well controlled.…”

Section: Temperature Gradientmentioning

confidence: 99%

“…A transverse temperature gradient can be present in some directional annealing studies, especially with large samples and using induction heating, in which a transverse temperature gradient is induced by the skin effect. Using the finite element method, Liu et al [54] showed that for a five-turn induction coil furnace (cross-section of 60 × 60 mm 2 ), a transverse temperature gradient was observed when the iron sample diameter was larger than 20 mm and that it increased with increasing sample Air-impingement cooling 844 [15] Induction coil Ambient air cooling 25 [35] Focused light radiation Ambient air cooling 50 [35][36][37]43,53,53,55,56] Focused light radiation Water-cooled copper 1000 [38][39][40][41][42]44,48] Induction coil Liquid Ga-In cooling bath 200-350 [45,47] Resistance heating Ambient air cooling 82 [46] Induction coil Water cooling bath 900 [49] Induction coil Water-cooled chill block 200 [55] Induction coil Water cooling bath 680 [57] Induction coil Ambient air cooling 180 diameter. Thus, a transverse temperature gradient can undoubtedly affect the directional recrystallised structure in different parts of the material.…”

Section: Temperature Gradientmentioning

confidence: 99%

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Directional recrystallisation processing: a review

Yang

Baker

2020

International Materials Reviews

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Directional recrystallisation processing is a solid-state process in which a specimen traverses a sharp hot zone and one or a few grains grow as they pass through the hot zone. The mechanism can be either a primary recrystallisation or secondary recrystallisation process, or a combination of both. The mechanism can be either primary recrystallisation or secondary recrystallisation process, or a combination of both. Directional recrystallisation was invented more than 80 years ago to achieve columnar grain structures or single crystals that have enhanced mechanical properties. This review discusses the effects of both processing parameters, including the temperature gradient, hot-zone velocity, and annealing temperature, and microstructural parameters, including stored energy, grain size, initial texture, solutes, and both soluble and insoluble particles, on the resulting microstructures. The results of simulations of directional recrystallisation, including Monte Carlo simulations, Front-Tracking methods, and phase-field simulations, are also reviewed. Finally, the effects of directional recrystallisation on material properties are discussed.

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Section: Temperature Gradientmentioning

confidence: 99%

Section: Temperature Gradientmentioning

confidence: 99%

Section: Temperature Gradientmentioning

confidence: 99%

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Directional recrystallisation processing: a review

Yang

Baker

2020

International Materials Reviews

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“…Subsequently, the hot extrusion of mechanical alloyed powders is conducted to form a consolidated ODS superalloy bar with a fine primary recrystallized microstructure. Then, the directionally recrystallized microstructure with large millimeter-scale elongated grains is achieved by a specific high-temperature directional annealing known as "zone annealing," [16,17] with a final appropriate aging treatment to precipitate γ 0 phase. During each step of processing, the microstructure of the superalloy changes considerably in respect of grain size, deformation, oxide particle dispersion, γ 0 distribution, etc.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Processing Conditions on the γ′ Morphology of an Oxide Dispersion Strengthened Ni‐Based Superalloy

et al. 2020

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Herein, the evolution of the microstructure of a newly developed oxide dispersion strengthened (ODS) Ni‐based superalloy with emphasis on γ′ morphology during different processing conditions is investigated. X‐ray analysis of severely deformed mechanically alloyed (MAed) powders shows that the as‐milled nano‐sized crystallite size increases with annealing associated with the sharp drop of dislocation density. At the same time, by annealing MAed powders γ′ precipitates above 300 °C, and depending on the aging treatment regime, Vickers microhardness changes mainly due to γ′ distribution and dislocation release. The thorough evaluation of γ′ morphology in the microscale shows that in contrast to the spherical shape of γ′, after heat treatment of solutionized MAed ODS superalloy, irregular‐shaped γ′ exist in the MAed ODS superalloy due to severe plastic deformation during mechanical alloying. However, a unique nanostructured lamellar morphology forms in the γ′ precipitates with different lamellae directions. This structure is stable in all subsequent processing steps with γ′ lamellae of (011true¯) planes and intervals of 20–30 nm. The scanning transmission electron microscopy (STEM)–high‐angle annular dark‐field (HAADF) composition analysis clarifies that the nanostructured lamellar morphology shows no partitioning of alloying elements, and its origin may be attributed to the formation of antiphase domain boundaries.

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“…Depending on the base metal there are a number of different ODS alloys for turbine system material applications. Among them, the major commercial and experimental ODS alloys are Nibased, Fe-based, and Co-based alloys having a basic alloy systems of NiCrAl, FeCrAl, and CoCrAl respectively [16][17][68][69][70][71][72][73].…”

Section: Ods Alloy Typesmentioning

confidence: 99%

Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

Amare¹

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Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling Belachew N. Amare Due to the need to increase the efficiency of modern power plants, land-based gas turbines are designed to operate at high temperature creating harsh environments for structural materials. The elevated turbine inlet temperature directly affects the materials at the hottest sections, which includes combustion chamber, blades, and vanes. Therefore, the hottest sections should satisfy a number of material requirements such as high creep strength, ductility at low temperature, high temperature oxidation and corrosion resistance. Such requirements are nowadays satisfied by implementing superalloys coated by high temperature thermal barrier coating (TBC) systems to protect from high operating temperature required to obtain an increased efficiency. Oxide dispersive strengthened (ODS) alloys are being considered due to their high temperature creep strength, good oxidation and corrosion resistance for high temperature applications in advanced power plants. These alloys operating at high temperature are subjected to different loading systems such as thermal, mechanical, and thermo-mechanical combined loads at operation. Thus, it is critical to study the high temperature mechanical and microstructure properties of such alloys for their structural integrity. The primary objective of this research work is to investigate the mechanical and microstructure properties of nickel-based ODS alloys produced by combined mechano-chemical bonding (MCB) and ball milling subjected to high temperature oxidation, which are expected to be applied for high temperature turbine coating with micro-channel cooling system. Stiffness response and microstructure evaluation of such alloy systems was studied along with their oxidation mechanism and structural integrity through thermal cyclic exposure. Another objective is to analyze the heat transfer of ODS alloy coatings with micro-channel cooling system using finite element analysis (FEA) to determine their feasibility as a stand-alone structural coating. During this project it was found that stiffness response to increase and remain stable to a certain level and reduce at latter stages of thermal cyclic exposure. The predominant growth and adherent Ni-rich outer oxide scale was found on top of the alumina scale throughout the oxidation cycles. The FEA analysis revealed that ODS alloys could be potential high temperature turbine coating materials if micro-channel cooling system is implemented.

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Directional recrystallization of ODS alloys by means of zone annealing

Cited by 14 publications

References 7 publications

Directional recrystallisation processing: a review

Directional recrystallisation processing: a review

Evaluation of Processing Conditions on the γ′ Morphology of an Oxide Dispersion Strengthened Ni‐Based Superalloy

Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

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