A tight-binding analysis of cohesive properties in the Ni-Al system

Colinet, C.; Bessoud, A; Pasturel, A.

doi:10.1088/0953-8984/1/34/002

Cited by 18 publications

(4 citation statements)

References 18 publications

(18 reference statements)

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“…It is obvious that Ni 3 Al alloys exhibit a transition from the fully ordered to the disordered state with some degree of SRO at about 800-850 • C. The magnitudes of the LRO and the SRO parameters of α 1 calculated, with a 95% confidence level, below 850 • C have justified the existence of almost perfect L1 2 -type ordering in Ni 3 Al alloys. The predicted values of the LRO and the SRO parameters calculated for a temperature range under consideration where Ni 3 Al intermetallics eventually exhibit L1 2 -type ordering, agree well with the theoretical magnitudes of the ordering parameters as well as with the results of the ground state calculations at low temperatures [15,16,36]. However, the order-disorder transition temperature obtained from figure 4 shows a deviation from the experimentally determined value.…”

Section: Effects Of Temperature and Al Concentration On Ordering Char...supporting

confidence: 80%

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni₃Al intermetallics

Mekhrabov¹,

Akdeniz²

2006

Modelling Simul. Mater. Sci. Eng.

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The evolution of atomic ordering processes in Ni3Al has been modelled by a Monte Carlo (MC) simulation method combined with the electronic theory of alloys in pseudopotential approximation. The magnitudes of atomic ordering energies of atomic pairs in the Ni3Al system have been calculated by means of electronic theory in pseudopotential approximation up to the 4th coordination spheres and subsequently used as input data for MC simulation for more detailed analysis for the first time. The Bragg–Williams long-range order (LRO) and Cowley–Warren short-range order (SRO) parameters have been calculated from the equilibrium configurations attained at the end of the MC simulation for each predefined temperature and Al concentration levels which reveal the evolution of the system from the L12 → disordered state as the temperature increases. The values of the LRO and SRO parameters at temperatures below 800 °C justify the existence of L12-type ordered Ni3Al alloys for all concentration levels whereas at temperatures above 850 °C, the values of the LRO parameter implies the presence of a disordered solid solution of Ni3Al alloys. However, a higher degree of the SRO order parameter above the predicted order–disorder transition temperature is preserved up to the melting point of Ni3Al intermetallics. The composition dependence of the LRO and SRO parameters agrees well with the experimental results.

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Section: Effects Of Temperature and Al Concentration On Ordering Char...supporting

confidence: 80%

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni₃Al intermetallics

Mekhrabov¹,

Akdeniz²

2006

Modelling Simul. Mater. Sci. Eng.

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“…Tight-binding models also have been used to model the Ni-Al phase diagram. 23 There have been several previous electronic structure calculations of Ni 3 Al ͑Refs. 13,17-19, and 22͒ and NiAl ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

“…38,23 . The preference for Ni-Al pairs over Al-Al nearest neighbors can be readily explained by the effect of the sp-d hybridization on the fourth moment of the LDOS.…”

Section: Introductionmentioning

confidence: 99%

Connections between the electron-energy-loss spectra, the local electronic structure, and the physical properties of a material: A study of nickel aluminum alloys

1998

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The local electronic structure of a material can be determined from the energy-loss spectrum of a swift electron beam scattered through it. When the electron beam is focused down to the width of an atomic column, the electronic density of states ͑DOS͒ at an interface, grain boundary, or impurity site can be decomposed by site, chemical species and angular momentum. Here we discuss the use of electron-energy-loss spectroscopy ͑EELS͒ fine structure to provide insight into the origin of grain boundary and interfacial properties reported earlier ͓D. A. Muller et al., Phys. Rev. Lett. 75, 4744 ͑1995͔͒ for Ni 3 Al. We examine the electronic structure trends in Ni-Al compounds, both experimentally with the EELS measurements and theoretically, using ab initio band-structure calculations. The conditions under which the band-structure calculations can quantitatively reproduce the EELS measurements ͑and in particular, the question of just which local DOS is being measured͒ are addressed. Cyrot-Lackmann's moments theorem provides a framework to explain the systematic changes in the local DOS on alloying. The shape changes in the near-edge fine structure of both the Ni and Al L edges are readily understood by the sensitivity of the fourth moment of the local DOS to the angular character of the Ni-Al bonding. The language of bond-order potentials proved useful in linking shape changes in the DOS to changes in cohesion. The consequences for formation energies and ordering trends in the transition-metal-aluminum alloys are also discussed.

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“…Insights into the bonding and hybridization in the system, however, can usually be obtained more clearly by working with localized basis functions and using the simpler tight-binding representation. [26][27][28] Recently we have shown that accurate tight-binding parameters can be obtained directly from the FPLMTO method. [29] In this paper we have used this method to perform a systematic study of impurities on NiAl.…”

Section: Introductionmentioning

confidence: 99%

Systematic first-principles study of impurity hybridization in NiAl

Djajaputra

Cooper

2002

Phys. Rev. B

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We have performed a systematic first-principles computational study of the effects of impurity atoms (boron, carbon, nitrogen, oxygen, silicon, phosporus, and sulfur) on the orbital hybridization and bonding properties in the intermetallic alloy NiAl using a full-potential linear muffin-tin orbital method. The matrix elements in momentum space were used to calculate real-space properties: onsite parameters, partial densities of states, and local charges. In impurity atoms that are empirically known to be embrittler (N and O) we found that the 2s orbital is bound to the impurity and therefore does not participate in the covalent bonding. In contrast, the corresponding 2s orbital is found to be delocalized in the cohesion enhancers (B and C). Each of these impurity atoms is found to acquire a net negative local charge in NiAl irrespective of whether they sit in the Ni or Al site. The embrittler therefore reduces the total number of electrons available for covalent bonding by removing some of the electrons from the neighboring Ni or Al atoms and localizing them at the impurity site. We show that these correlations also hold for silicon, phosporus, and sulfur.

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A tight-binding analysis of cohesive properties in the Ni-Al system

Cited by 18 publications

References 18 publications

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni₃Al intermetallics

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni₃Al intermetallics

Connections between the electron-energy-loss spectra, the local electronic structure, and the physical properties of a material: A study of nickel aluminum alloys

Systematic first-principles study of impurity hybridization in NiAl

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A tight-binding analysis of cohesive properties in the Ni-Al system

Cited by 18 publications

References 18 publications

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni3Al intermetallics

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni3Al intermetallics

Connections between the electron-energy-loss spectra, the local electronic structure, and the physical properties of a material: A study of nickel aluminum alloys

Systematic first-principles study of impurity hybridization in NiAl

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Modelling and Monte Carlo simulation of the atomic ordering processes in Ni₃Al intermetallics

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni₃Al intermetallics