Statistical ALCHEMI: Aeneral formulation and method with application to Ti[sbnd]Al ternary alloys

Rossouw, C. J.; Forwood, C. T.; Gibson, Mark; Miller, Peter

doi:10.1080/01418619608239690

Cited by 59 publications

(19 citation statements)

References 27 publications

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“…Although a compromise is achieved for several alloying elements such as Nb, Zr, and Ga, [16][17][18][19][20][21][22]24,26] there are significant disparities in site preference of Cr, Mn, and V [13,[15][16][17][18][19][23][24][25] in c-TiAl reported to date. Besides, there still remain various elements such as Cu, Zn, Ag, and Au, whose site occupations in c-TiAl are unexplored or not debated but worthy of investigation.…”

Section: Introductionmentioning

confidence: 99%

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

Aykol

Mekhrabov

Akdeniz

2009

Metall Mater Trans A

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MURATAHAN AYKOL, AMDULLA O. MEKHRABOV, and M. VEDAT AKDENIZSite selection and pseudo-clustering behaviors of the various M alloying elements in Al-lean Ti 50 Al 50-X M X (X = 1, 2, 3, 4, and 5 at. pct) intermetallics have been investigated by means of the ordering energy-dependent and long-range-order forced fast Monte Carlo simulation method. The ordering energies have been calculated via pseudopotential approximation in the electronic theory of alloys up to the third coordination sphere (CS) taking the anisotropic nature of tetragonal L1 0 -type structure of c-TiAl into account. It was shown that the site occupation characteristics of the M alloying element atoms in c-TiAl intermetallics are governed by the relative magnitude of partial ordering energies between Ti-M and Al-M atomic pairs. However, the sign of partial ordering energies of these atomic pairs at the first CS becomes important in determining the clustering behavior and controls the dissolution modes of alloying element atoms in the c-TiAl matrix. The pseudo-clustering behavior of alloying elements reveals three dissolution modes, namely, random dissolution (mode I), planar clustering in two dimensions (mode II), and three-dimensional (3-D) clustering (mode III) of the M occupant atoms.

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Section: Introductionmentioning

confidence: 99%

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

Aykol

Mekhrabov

Akdeniz

2009

Metall Mater Trans A

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“…However, the inaccuracies of numerical analysis when comparing experiment with calculated patterns does not re¯ect on the accuracy of statistical ALCHEMI, where numerical analysis of purely experimental results has been shown to be accurate (Rossouw et al, 1996;Anderson, 1997).…”

Section: Acta Cryst (2001) A57 321±332mentioning

confidence: 99%

“…the experimental pattern is simulated from a linear superposition of scaled calculated patterns, where the scaling factors are related to the occupancy of the particular sublattice site (Rossouw et al, 1996). The whole data set is then used to ®t Zn counts N where the factors k are ®tted constants and C an offset constant, and the fractional distribution F n of Zn over a sublattice site n is given by F n n a k k .…”

Section: Semi-quantitative Analysismentioning

confidence: 99%

“…Statistical ALCHEMI involves a reconstruction of experimental channelling contrast from minority species with a best-®t linear combination of host-atom ICPs, derived from the same experimental data set. Partitioning of the introduced minority species over substitutional sites, together with uncertainties, are subsequently derived from ®tted coef®cients and their standard deviations (Rossouw et al, 1996;Anderson, 1997). Calculated channelling patterns (Oxley et al, 1999), although providing insight into expected contrast, are not necessary for simple ALCHEMI.…”

Section: Introductionmentioning

confidence: 99%

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Location of Zn within the Mg₁₂(La_xCe_1−x) lattice by X-ray incoherent channelling patterns

et al. 2001

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Systematic electron diffraction studies on intermetallic precipitates formed within a lightweight Mg–RE–Zn alloy (RE La or Ce) identify these to be of structural type Mn12Th (space group ). Analytical electron microscopy yields an overall composition of Mg12(LaxCe1−x) with x ~ 0.43, with 1 at.% Zn incorporated within the lattice. Variations in characteristic X‐ray emission rates, as an electron beam is rocked near zone‐axis orientations, are used to form two‐dimensional channelling patterns, termed X‐ray incoherent channelling patterns. This channelling contrast enables a specific sublattice site that is occupied by Zn to be unambiguously identified within the Mg12RE lattice. The particular sublattice site is denoted by the Wyckoff letter f, and is one of the three different Mg sublattice sites f, i and j. Of these three sites, the Wigner–Seitz cell that is centred on the f sublattice site has the largest Mg–RE interatomic distance, and therefore the f site is expected to be favoured for accommodating the substitution of a larger Zn atom.

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“…Towards this objective, further information on the constitutional defect mechanism that operates in the T 2 phase is necessary. The data required to establish the defect mechanism will be determined by careful measurement and analysis of lattice parameter versus composition trends, and x-ray peak intensity analysis for specific reflections provides an insight into site occupancy determination [83Spe,88Pen,96Ros]. The identification of the operative defect mechanism together with the phase equilibria measurements will provide the basis for the formulation of a thermodynamic model for the T 2 phase.…”

Section: Thermodynamic Evaluationmentioning

confidence: 99%

Phase Stability in Ultra-High Temperature Refractory Metal Alloys and Coatings

Perepezko¹

2002

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Statistical ALCHEMI: Aeneral formulation and method with application to Ti[sbnd]Al ternary alloys

Cited by 59 publications

References 27 publications

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

Location of Zn within the Mg₁₂(La_xCe_1−x) lattice by X-ray incoherent channelling patterns

Phase Stability in Ultra-High Temperature Refractory Metal Alloys and Coatings

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Statistical ALCHEMI: Aeneral formulation and method with application to Ti[sbnd]Al ternary alloys

Cited by 59 publications

References 27 publications

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

Location of Zn within the Mg12(LaxCe1−x) lattice by X-ray incoherent channelling patterns

Phase Stability in Ultra-High Temperature Refractory Metal Alloys and Coatings

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Location of Zn within the Mg₁₂(La_xCe_1−x) lattice by X-ray incoherent channelling patterns