Creep resistance of CMSX-3 nickel base superalloy single crystals

Pollock, Tresa M.; Argon, A. S.

doi:10.1016/0956-7151(92)90195-k

Cited by 890 publications

(332 citation statements)

References 24 publications

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“…According to calculations of both von Mises stresses [30,31,32] and the more realistic pertinent resolved shear stresses [30] as well as experimental observations [2,3,14,16], the largest local (shear) stresses develop in the case of an applied tensile load, initially in the y-channels which lie perpendicular to the stress axis. Thus, tensile plastic yielding starts first in the horizontal y-channels, whereas the dislocations are stopped after glide at the y/y'-interfaces ( Fig.…”

Section: Theoretical Backmoundmentioning

confidence: 99%

Enhancement of the High-Temperature Tensile Creep Strength of Monocrystalline Nickel-Base Superalloys by Pre-rafting in Compression

Tetzlaff¹,

Mughrabi²

2000

Superalloys 2000 (Ninth International Symposium)

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In recent years, the development of Y.-hardened monocrystalline nickel-base superalloys focused on different aspects of alloy composition and microstructural refinement. In particular, the formation of so-called y/y'-raft structures, lying typically, in the case of a negative y/y'-lattice misfit 6, perpendicular to the stress axis during high-temperature tensile creep had attracted much attention. Unfortunately, this microstructural transformation leads in most cases to deteriorated creep properties. Earlier attempts to prevent rafting by suitable prior annealing treatments had been in so far unsuccessful, that while the applied annealing treatment retarded raft formation, it inevitably lead to microstructural coarsening accompanied by creep acceleration. The goal of the present extensive study is to show that suitable pre-rafting in compression, leading to a y/y'-raft structure parallel to the stress axis in the case of a negative lattice misfit, enhances not only the isothermal hightemperature fatigue strength, as shown earlier, but also the hightemperature creep properties. The observed macroscopic creep behaviour will be discussed with reference of microstructural observations.

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Section: Theoretical Backmoundmentioning

confidence: 99%

Enhancement of the High-Temperature Tensile Creep Strength of Monocrystalline Nickel-Base Superalloys by Pre-rafting in Compression

Tetzlaff¹,

Mughrabi²

2000

Superalloys 2000 (Ninth International Symposium)

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“…Increased alloying with Re and W has resulted in superalloys with a negative -' lattice misfit, due to the strong partitioning behavior of these elements to the phase [7]. There has been much discussion in the literature regarding the relationship between the -' lattice misfit and the creep resistance of superalloys [8][9][10][11]. Though superalloys with a more negative misfit have generally been observed to be more creep resistant, a balance of properties, including solid solution strengthening of the matrix and strength of the ' are also important [12].…”

Section: Introductionmentioning

confidence: 99%

Microstructural Stability and Creep of Ru-Containing Nickel-Base Superalloys

Rowland¹,

Feng²,

Pollock³

2004

Superalloys 2004 (Tenth International Symposium)

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Nickel-base single crystal superalloys with Ru additions of 5.7 to 9.7 wt%, moderate amounts of refractory elements and up to 6.7 wt% Cr were investigated. The ' precipitate morphology of the experimental alloys was cuboidal, near-spherical and intermediately-shaped depending on the Cr and Ru content. The time to 1% creep and the creep rupture lives of the experimental alloys were measured at 950°C and 290 MPa. Within the set of alloys investigated rafting occurred parallel to the axis of the applied uniaxial tensile stress, perpendicular to the applied stress or was completely suppressed, suggesting a wide range of lattice misfit. Interfacial dislocation network development during creep also varied widely among the alloys investigated. The possibilities for control of microstructure and high temperature properties via Ru additions are discussed.

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“…Under these conditions, a number of degradation mechanisms can arise which are usually mediated by diffusional processes. For example, creep deformation occurs at a rate dependent upon diffusional rearrangements at dislocation cores [1]. Directional coarsening of the γ phase (the so-called rafting effect) requires mass transport on the scale of the periodicity of the γ precipitates [2].…”

Section: Introductionmentioning

confidence: 99%

On the Diffusion of Alloying Elements in the Nickel-Base Superalloys

Fu¹,

Reed²,

Janotti³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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The diffusion of transition metal solutes in nickel has been studied using quantum-mechanical first principles methods, and the predictions compared critically with the experimental data available in the literature. For the 4d and 5d rows which contain Ru and Re respectively, diffusion rates are largest for elements at the far west and far east of the d-block of transition metals. The calculations reveal that this is due to a significant barrier energy for solute-vacancy exchange for elements residing at the centre of the period, e.g. Ru and Re, despite their displaying atomic sizes which are closest to that of Ni. Thus it is demonstrated conclusively that the underlying electronic bonding controls the rate of diffusion. Elements such as Ru and Re are amongst the most dense and least compressible of the transition metals due to their configuration of electrons -when alloyed with Ni this causes directional and incompressible Ni-Ru and Ni-Re bonds to be formed which hinder vacancy migration. These effects dominate over any differences in the vacancy-solute binding energy and any influence of the atomic radius of the solute. In this respect, the results disprove the traditional view that diffusion of substitutional solutes is least rapid when the size misfit with the host is the greatest. The trends for the 3d row are also studied, and it is shown that magnetism has a profound effect. Finally, if the theoretical results are to be rationalised with the experimental data, it is demonstrated that the correlation factor -which accounts for diffusional jumps in the reverse direction -should be included in the model. The results explain why some elements -for example Re -have a strong effect on the high temperature properties of the superalloys, and provide insights for future alloy design efforts.

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Creep resistance of CMSX-3 nickel base superalloy single crystals

Cited by 890 publications

References 24 publications

Enhancement of the High-Temperature Tensile Creep Strength of Monocrystalline Nickel-Base Superalloys by Pre-rafting in Compression

Enhancement of the High-Temperature Tensile Creep Strength of Monocrystalline Nickel-Base Superalloys by Pre-rafting in Compression

Microstructural Stability and Creep of Ru-Containing Nickel-Base Superalloys

On the Diffusion of Alloying Elements in the Nickel-Base Superalloys

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