Thermodynamic Factor Evaluated from Diffuse X-ray Scattering

Liubich, Vlad; Dorfman, Simon; Fuks, David; Mehrer, H.

doi:10.2320/matertrans1989.40.132

Cited by 15 publications

(11 citation statements)

References 17 publications

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“…The underlying theory was worked out many years ago by Darken [30] and involves a parameter that must be obtained from independent thermodynamic studies-the thermodynamic factor, ⌽, which, for a true binary system is defined as [19] Liubich et al [31] have shown how, in the case of B2-FeAl, ⌽ bin can be obtained from diffuse X-ray scattering and there have been several model calculations (for example, Dorfman et al [32] and Ikeda et al [33] ). Now it is clear from Eq.…”

Section: Thermodynamic Factors For Diffusionmentioning

confidence: 99%

Thermodynamic properties and diffusion thermodynamic factors in B2-NiAl

Bencze

Raj

Kath

et al. 2004

Metall Mater Trans B

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The vaporization of Ni-Al alloys has been investigated in the temperature range 1178 to 1574 K by Knudsen effusion mass spectrometry (KEMS). Thirteen different compositions have been examined in the composition range 38 to 57 at. pct Al. The partial pressures and thermodynamic activities of both Ni and Al have been evaluated both directly from the measured ion intensities for a component in both the alloy and the pure element, , and also from the ion intensity ratios of the alloy components, , by means of a Gibbs-Duhem integration. Reliable partial molar enthalpies and entropies for both components have been obtained by mass spectrometry for this system for the first time. Both properties are found to be nearly temperature independent over the wide temperature range investigated. Two separate component diffusion thermodynamic factors have also been evaluated for the first time by taking into account the large vacancy concentrations in these alloys. The enthalpy and Gibbs energy of mixing of stoichiometric Ni 0.5 Al 0.5 at 1400 K, evaluated using the Gibbs-Duhem ion intensity ratio (GD-IIR) method, are Ϫ78.4 Ϯ 1.2 and Ϫ49.0 kJ/mol, respectively, with Al(liquid) and completely paramagnetic Ni(fcc, cpm) as reference states.

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Section: Thermodynamic Factors For Diffusionmentioning

confidence: 99%

Thermodynamic properties and diffusion thermodynamic factors in B2-NiAl

Bencze

Raj

Kath

et al. 2004

Metall Mater Trans B

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“…In the ordered B2 structure, the Fe and Al atoms form interpenetrating primitive cubic lattices. Although the Fe-Al alloys remain ordered at elevated temperatures even at the melting point, the exact state of order is a function of temperature from the viewpoint of thermodynamics [5,17]. As the temperature increases, more and more atoms on the…”

Section: On the Mechanisms Of The If Peaksmentioning

confidence: 99%

Anelasticity correlated to vacancies in B2 Fe–Al alloys

Wang

Han

Gao

et al. 2006

Physica Status Solidi (a)

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Internal friction behaviors of B2 Fe -Al alloys were examined to understand the correlation between the anelasticity and thermal vacancies. Three internal friction peaks were found in the rapidly cooled specimens at around 210 °C (P1), 410 °C (P2) and 520 °C (P3), respectively, while in the slowly cooled specimens, the P1 peak was significantly decreased and the P2 peak was decomposed into two peaks (P2 L and P2 H ). All the internal friction peaks showed relaxational nature and they shifted toward high temperature with increasing frequency. It is suggested that the P1 peak originates from the reorientation of the divacancies composed of Fe vacancies and the nearest-neighboring Al vacancies, the P2 L peak from the dissociation and diffusion of the interstitial carbon atoms from the carbon-vacancy complexes and the P2 H peak from the reorientation of the triple defects.

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“…Corresponding to the presence of the peak, the RDM showed a rapid drop with increasing temperatures and it became relatively smooth during the subsequent cooling measurements. It is noted that a minimum in the RDM can be seen at about 500 C during heating, which is probably correlated to a process of increasing the degree of order since the exact degree of order decreases with increasing temperature in B2 FeeAl alloys [14,15]. Moreover, the so-called KronigeKramers' relation also contributes to the change in the RDM [16,17].…”

Section: Methodsmentioning

confidence: 98%