Thermodynamic calculation for alloy systems

Ding, Xueyong; Wang, Wenzhong; Fan, Peng

doi:10.1007/s11663-999-0056-z

Cited by 50 publications

(63 citation statements)

References 8 publications

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“…Equation (18) shows the relation among equations (2), (12), (14) and (16), so the standard Gibbs free energy change of equation (2) (J mol 21 ), shown in equation (20), is obtained by equation (19) Eq : (2)~Eq : (12) Equation (21) is the same temperature equation as in the chemical reaction. By combining equations (11), (20) and (21), equation (22), the relation between the solubility of Nb in the melt and the absolute temperature when equation (2) is balanced and the addition amount of Nb was 1?0 wt-%, is obtained.…”

Section: Discussionmentioning

confidence: 99%

Effect of niobium on primary carbides of hypereutectic high chromium cast iron

Xing

Wang

2013

Ironmaking & Steelmaking

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The effect of niobium on the primary M 7 C 3 carbides of a hypereutectic high chromium cast iron containing 4?0 wt-%C and 20?0 wt-%Cr was studied by means of optical microscopy, scanning electron microscope, X-ray diffraction, water quenching, and energy dispersive X-ray spectrometry. The primary carbides were refined as niobium content increased. Theoretical calculation and the experimental results indicate that NbC particles form before the precipitation of primary carbides when niobium is added to the alloy. The first precipitated NbC particles lead to a reduction of the hypereutectic degree and the solidification temperature range of the alloy and, therefore, lead to finer hypereutectic primary carbides. The first precipitated NbC particles can act as heterogeneous nuclei of the primary M 7 C 3 carbides, which also results in the refinement of the primary carbides.

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Section: Discussionmentioning

confidence: 99%

Effect of niobium on primary carbides of hypereutectic high chromium cast iron

Xing

Wang

2013

Ironmaking & Steelmaking

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“…The extremely strong Na-Na self-interaction that is expressed by the results in Figures 3 through 10 may be model [2,25,26] and has recently been applied and discussed by Ding et al [27] The right-hand side of Eq. [13] expresses the explained by formation of Na clusters, assumed to be a mixture of dimers, trimers, and polymers of sodium in liquid Al.…”

Section: Self-interaction Clustering and Concentration The Amount Omentioning

confidence: 99%

“…[13] are explained in detail in the literature. [2,[25][26][27] The values of these parameters for the Al-Na system are obedience to Henry's law in the liquid solubility region. Also, the results of Dubreuil and Pelton, [18] if interpreted as listed in Table III.…”

Section: Self-interaction Clustering and Concentration The Amount Omentioning

confidence: 99%

Thermodynamics of liquid Al-Na alloys determined by using CaF2 solid electrolyte

Hansen

Tuset

Haarberg

2002

Metall Mater Trans B

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The purpose of this work has been to establish activity data on sodium in liquid aluminum-sodium alloys at temperatures applied by the industry in liquid metal refining processes. A coulometric titration technique using a galvanic cell employing CaF 2 as a solid electrolyte has enabled measurements to be done under very clean and well-defined conditions over the entire range of compositions from highly diluted up to nearly sodium-saturated solutions. Sodium in liquid aluminum of 99.9999 pct purity is found to exhibit strong negative deviation from Henry's law, corresponding to a large negative self-interaction coefficient Na Na as expressed by the equation Na Na ϭ 16,318 Ϫ (191.1 и 10 5 K) и T Ϫ1 . This behavior is normal for elements, which exhibit strong positive deviation from Raoult's law and is explained by formation of Na clusters. The activity coefficient at infinite dilution, ␥ o Na , is expressed by the equation: RT ln ␥ o Na ϭ 86,729 Ϫ 26.237T. The magnitude of ␥ o Na from this equation agrees with the value predicted from the Miedema's semiempirical model. Sodium in liquid Al-Si5 pct alloy of 99.9999 pct purity exhibits strong positive deviation from Henry's law, which is in agreement with earlier investigations of the activity of sodium in liquid Al-Si alloys. The activity coefficient of sodium in pure liquid aluminum at saturation, ␥ sat Na , is expressed by RT ln ␥ sat Na ϭ Ϫ67,476 ϩ 102.33T, which gives for the sodium concentration at saturation x sat Na ϭ exp (8115.5/T Ϫ 12.307). This implies that the solubility of sodium in liquid aluminum at temperatures around the melting point of aluminum is about 10 times higher than previously reported and decreases rapidly with increasing temperature, possibly due to a decreasing stability of Na clusters. Analysis of the experimental conditions used by previous investigators supports these findings.

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“…(4) and (5), the molar excess formation free energy at 873 K was calculated as ) can be obtained from the γ Pr by the thermodynamic deductions [13][14][15][16].…”

Section: Resultsmentioning

confidence: 99%