Ni and Al diffusion in Ni-rich NiAl and the effect of Pt additions

Marino, Kristen A.; Carter, Emily A.

doi:10.1016/j.intermet.2010.03.044

Cited by 19 publications

(19 citation statements)

References 41 publications

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“…This observation is in agreement with the recent reports of Hazel et al [31] who reported reduced wall consumption in superalloy components coated with NiAleCreZr overlay coatings in comparison to platinum aluminides. Recent first-principles quantum mechanics simulations have shown that Pt, in spite of its positive influence on oxide scale adherence, increases the diffusivities of both Ni and Al within the bulk [110,111]. Such reductions could have a significant impact on superalloy and TBC service lifetimes and component reparability.…”

Section: Discussionmentioning

confidence: 99%

Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

2011

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Section: Discussionmentioning

confidence: 99%

Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

2011

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“…For Ni concentrations slightly above 50%, the ASB mechanism will lead only to a local enhancement, but for alloys with a high enough concentration of Ni, a percolation threshold of Ni antisite atoms is reached, and the ASB mechanism could contribute to longrange Ni diffusion (53). We predicted that the ASB mechanism is indeed viable for Ni diffusion in Ni-rich NiAl, with a smaller activation energy (approximately 2.2-2.3 eV compared to 3 eV in stoichiometric NiAl), depending on the direction of overall atomic motion (57). Although our model alloy was only 53 at.…”

Section: Resultsmentioning

confidence: 90%

“…However, the substantial decreases in the defect formation energies produce large increases in the diffusion rate because these energies appear in the exponential of the diffusion coefficient. Therefore, Pt enhances Ni and Al diffusion by stabilizing the point defects and defect clusters that are intermediate minima along the diffusion pathways (52,55,57).…”

Section: Resultsmentioning

confidence: 99%

Atomic-scale insight and design principles for turbine engine thermal barrier coatings from theory

Marino

Hinnemann

Carter

2011

Proc. Natl. Acad. Sci. U.S.A.

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To maximize energy efficiency, gas turbine engines used in airplanes and for power generation operate at very high temperatures, even above the melting point of the metal alloys from which they are comprised. This feat is accomplished in part via the deposition of a multilayer, multicomponent thermal barrier coating (TBC), which lasts up to approximately 40,000 h before failing. Understanding failure mechanisms can aid in designing circumvention strategies. We review results of quantum mechanics calculations used to test hypotheses about impurities that harm TBCs and transition metal (TM) additives that render TBCs more robust. In particular, we discovered a number of roles that Pt and early TMs such as Hf and Y additives play in extending the lifetime of TBCs. Fundamental insight into the nature of the bonding created by such additives and its effect on high-temperature evolution of the TBCs led to design principles that can be used to create materials for even more efficient engines.A ircraft and power plants share a common source of usable energy: Both employ turbine engines that combust fuel to either propel airplanes or produce electricity. At a time in which efficient use of energy is paramount, improving the efficiency of turbine engines is one means to contribute to this global challenge. Turbine engines operate via the Brayton cycle, which offers lower carbon dioxide emissions and lower cost for power generation than other possible alternatives. Their efficiency can be increased by increasing the inlet temperature, which allows more expansion of gas that creates more pressure to drive the turbine. However, high-temperature operation, under oxidizing conditions, poses serious demands on the materials used to construct jet engine components. Materials must be found that are robust under such harsh operating conditions. Engineers over the past few decades have improved greatly the thermomechanical properties of the metal alloy comprising, e.g., the turbine blades, and have created a multilayer coating for the blades that protects against both heat and corrosion, referred to as a thermal barrier coating (TBC). These materials advances, along with internal component cooling, have been astonishingly successful, allowing the gas temperature to exceed the melting point of the metal alloy from which the engine components are constructed! Despite these advances, more robust TBCs are desired, either to extend TBC service lifetime under present-day operating conditions or to operate at even higher temperatures to achieve more efficient energy conversion. As a result, characterization and optimization of TBC properties have continued to be active areas of research. As is the case for most materials development, the usual path to improve TBCs relies on trial and error. Many materials compositions are fabricated, characterized, and tested. Unfortunately, characterization typically is performed postmortem, as virtually no instruments exist to characterize a TBC in situ during operation. The lack of in situ probes makes...

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“…Kao and Chang [70] proposed the antistructure bridge mechanism as an atomic mechanism of diffusion on the Ni-rich side. Marino and Carter [52] studied this by first-principles density functional theory calculations and found that the diffusion rate of Ni should increase with the increase Ni content on the Ni-rich side because of increase in the concentration of Ni antisites. This was indeed found by the tracer diffusion measurements [71].…”

Section: (Iii)mentioning

confidence: 99%

“…Therefore, defects must have a dominating role over the thermodynamic factor. Marino and Carter [52] calculated the defect formation and migration energies for diffusion of Ni and Al in the presence of Pt. The values are given in Table 1.…”

Section: (Iii)mentioning

confidence: 99%

Diffusion-Controlled Growth and Microstructural Evolution of Aluminide Coatings on Superalloys and Steel

Paul

2017

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The diffusion-controlled growth and microstructural evolution at the interface of aluminide coatings and different substrates such as Ni-base superalloys and steel are reviewed. Quantitative diffusion analysis indicates that the diffusion rates of components in the -NiAl phase increases with the addition of Pt. This directly reflects on the growth rate of the interdiffusion zone. The thickness and formation of precipitates between the bond coat and the superalloys increase significantly with the Pt addition. Mainly Fe 2 Al 5 phase grows during hot dip aluminization of steel along with few other phases with very thin layer. Chemical vapor deposition process is being established for a better control of the composition of the Fe-aluminide coating on steel.

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Ni and Al diffusion in Ni-rich NiAl and the effect of Pt additions

Cited by 19 publications

References 41 publications

Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

Influences of chromium and hafnium additions on the microstructures of β-nial coatings on superalloy substrates

Atomic-scale insight and design principles for turbine engine thermal barrier coatings from theory

Diffusion-Controlled Growth and Microstructural Evolution of Aluminide Coatings on Superalloys and Steel

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