Abnormal grain growth behavior of an Oxide Dispersion Strengthened Superalloy

Mino, Kazuaki; Nakagawa, Y. G.; Ohtomo, Akira

doi:10.1007/bf02646920

Cited by 23 publications

(21 citation statements)

References 12 publications

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“…< 100) texture has been reported to be formed in Ni-20wt%Cr-0.4wt%Y2O3,14,15) while (110> in most alloys containing high volume fraction of " phase. 13,14) No significant texture was observed for the present alloys in the as-extruded condition and zone annealing was necessary to obtain large elongated grain structures. These two results are again similar to the behavior of r'-containing alloys.…”

Section: Mechanical Alloying Process In Attritormentioning

confidence: 83%

An Oxide Dispersion Strengthened Nickel-base Superalloy with Excellent High Temperature Strength

Mino¹,

Asakawa²

1987

ISIJ Int.

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SynopsisOxide dispersion strengthened nickel-base superalloys with compositional variants were prepared by mechanical alloying, and their secondary recrystallization characteristics and creep rupture strength were examined. Their matrix compositions were determined by modifying cast superalloys containing a high volume fraction of " phase. One of the presently investigated alloys, Alloy 98, was shown to form directionally recrystallized grain structures by zone anneal and surpass monocrystalline superalloys in the creep rupture stress range below about 320 MPa. Higher tantalum concentration in Alloy 98 than in other oxide dispersion strengthened alloys is considered to improve creep rupture strength. Aluminum addition, higher than about 6 wt%, seems to degrade recrystallization properties and consequently decrease creep strength. M23Cs carbide precipitates besides " phase and oxide dispersoids were observed in Alloy 98 by means of transmission electron microscopy. Also observed was a formation of coalescent oxides and oxide denuded areas around them, and the higher creep strength will be expected by improved process to minimize these dispersion defects.

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Section: Mechanical Alloying Process In Attritormentioning

confidence: 83%

An Oxide Dispersion Strengthened Nickel-base Superalloy with Excellent High Temperature Strength

Mino¹,

Asakawa²

1987

ISIJ Int.

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“…Development of such grain morphology has been correlated with the alignment of dispersoids along the extrusion axis, which restricts lateral growth of grains [11]. This type of elongated grain structure is commonly observed after isothermal annealing or zone annealing of ODS superalloys [7,9,11]. …”

Section: Resultsmentioning

confidence: 99%

“…However, grain boundary sliding accommodated by either diffusion or dislocation creep mechanism is always expected at high temperatures [7,8], which implies that a large grain size is preferred in creep resistant materials as in the case of MA superalloys [9]. The larger grains containing finely dispersed oxides can be effectively developed by secondary recrystallization [10].…”

Section: Introductionmentioning

confidence: 99%

Creep in grain coarsened ODS MA NiAl

Suh²,

Nash

2002

Met. Mater. Int.

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NiAl based oxide dispersion strengthened (ODS) intermetallic alloys have been produced by mechanical alloying (MA) and consolidated by hot extrusion. Subsequent isothermal annealing was carried out to induce normal grain growth (NGG), and a thermomechanical treatment was performed to induce secondary recrystallization (SRx). SRx resulted in pronounced elongated grain growth without dispersoid coarsening, whereas concurrent equiaxed coarsening of grains and dispersoids occurred in NGG specimens. Creep properties of grain coarsened ODS MA NiAl were investigated, and the associated creep mechanisms were evaluated. The creep properties of SRxed MA NiAl are compared with those of as-consolidated MA NiAl and other counterparts. It has been shown that SRx results in improved creep resistance compared to NGG mechanism. The apparent activation energy and the stress exponent for creep indicate that SRx MA NiAl exhibits intermediate creep behavior of the two limiting dislocation creep modes; climb controlled and viscous glide controlled. However, a grain size dependent creep has been shown, indicating that grain boundary sliding mechanism contributes to the overall deformation in MA NiAl.

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“…For example, Cline [12] produced single-crystal silicon in a thin polycrystal films with the starting grain size of 0.03 μm and without cold work at temperatures near the melting point at hot zone velocities from 3 to 30 mm h −1 , and Zhang et al [38,44,48] found that cold work was not needed to produce columnar grains during directional recrystallisation of both fine-grained (∼50 μm) Fe and Fe-6.5 wt-% Si with elongated (125 × 35 μm) grains. Similarly, large columnar grains have been produced from hot extruded and/or hot-rolled, fine-grained (0.2-0.4 μm), low-dislocation-density superalloys such as IN-853 [9], IN-748 [10], MA 6000E [11], TMO-2 [15], MA 6000 [17,19,25,29], PM3030 [24], SRR99 [30], and MA 754 [43] via directional secondary recrystallisation using annealing temperatures from 0.6 to 0.9 T m .…”

Section: Directional Primary Recrystallisation or Directional Seconda...mentioning

confidence: 99%

“…The lower processing temperatures required for directional recrystallisation allow easier processing of high melting point materials such as tungsten [5,6]; . It is likely that minimal solute redistribution will occur, allowing single crystals or columnar grain structures to be produced from non-castable alloys, such as advanced nickel-based superalloys [7][8][9][10][11]13,[15][16][17][18][19][20][23][24][25][27][28][29][30][31]43,46,50,51], and avoiding the homogenisation anneals that are required to remove the interdendritic segregation that occurs in single crystals of nickel-based superalloys grown by directional solidification, again potentially producing cost savings; . Complex net-shaped (but not re-entrant geometry) structures can, in principle, be processed, producing cost savings compared to directional solidification by avoiding the need for costly moulds and cores [13,66,75], see, for example, the hollow turbine blade with cooling holes shown in Figure 2 [75]; .…”

Section: Introductionmentioning

confidence: 99%

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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Abnormal grain growth behavior of an Oxide Dispersion Strengthened Superalloy

Cited by 23 publications

References 12 publications

An Oxide Dispersion Strengthened Nickel-base Superalloy with Excellent High Temperature Strength

An Oxide Dispersion Strengthened Nickel-base Superalloy with Excellent High Temperature Strength

Creep in grain coarsened ODS MA NiAl

Directional recrystallisation processing: a review

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