Thermodynamic calculation on the miscibility gap of fcc-Al based solid solution in the Al–Zn–Cu system

Dai, Lin; Li, H.X.; Ren, Yuping

doi:10.1016/j.jallcom.2008.11.076

Cited by 5 publications

(4 citation statements)

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“…All these thermodynamic constants are shown in Table 1 3 . Interaction parameters values were determined and kept constant for each alloy composition and temperature.…”

Section: Numerical Methodologymentioning

confidence: 99%

“…The spinodal decomposition mechanism has been reported [1][2][3] to occur in the Al-Zn and Al-Zn-Cu alloy systems. Furthermore, this phase transformation is associated with the strengthening of both Al-rich and Zn-rich alloys [4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

“…The spinodal decomposition is also normally related to the presence of a miscibility gap which is present in both Al-Zn and Al-Zn-Cu alloys. In fact, the copper addition has been pointed out 2,3 to increase the temperature of the miscibility gap.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, it has been difficult to study experimentally the spinodal decomposition in the early stages of aging in the binary alloys. To slow the spinodal decomposition kinetics, the addition of copper has been used in several works 2,3 .…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Spinodal Decomposition in Al-Zn and Al-Zn-Cu Alloys Using the Nonlinear Cahn-Hilliard Equation

et al. 2017

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The phase field model based on the nonlinear Cahn-Hilliard equation was applied to analyze the spinodal decomposition process in Al-Zn and Al-Zn-Cu alloys. Partial differential equations were solved using the explicit finite difference method for the Al-20, and 35 at. % Zn alloys aged at temperatures between 25 and 100 °C for times from 10 s to 2000 s and Al-20at.%Zn-10at.%Cu and Al-20at.%Zn-5at.%Cu alloys at temperatures between 400 and 500 °C for times from 3600 to 360000 s. ThermoCalc indicated that the copper addition extends the presence of the metastable miscibility gap up to a temperature of about 597 °C in comparison to the temperature of 350 °C for the binary case. This miscibility gap was calculated assuming that the equilibrium phases were not present and thus it is only existing at the early stages of aging. Simulation results pointed out that the phase decomposition process is much faster in the binary alloys than that in the ternary alloys in spite of the higher aging temperature for the latter case.

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“…All these thermodynamic constants are shown in Table 1 3 . Interaction parameters values were determined and kept constant for each alloy composition and temperature.…”

Section: Numerical Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Analysis of Spinodal Decomposition in Al-Zn and Al-Zn-Cu Alloys Using the Nonlinear Cahn-Hilliard Equation

et al. 2017

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Al-Cu-Zn (Aluminum-Copper-Zinc)

Raghavan¹

2009

J. Phase Equilib. Diffus.

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The previous update on this ternary system by [2007Rag] reviewed mainly the thermodynamic assessment of [1998Lia]. Very recently, [2009Ren] determined a partial isothermal section at 360°C for Cu-lean alloys and found that Cu stabilizes the miscibility gap of the Al-Zn fcc phase. Binary SystemsThe Al-Cu phase diagram [2004Ria] depicts the following intermediate phases: CuAl 2 (C16-type tetragonal, denoted h), CuAl(HT) (g 1 , orthorhombic) CuAl(LT) (g 2 , monoclinic), Cu 5 Al 4 (HT) (f 1 , orthorhombic, space group Fmm2), Cu 5 Al 4 (LT) (f 2 , orthorhombic, space group Imm2), e 1 (HT) (cubic?), e 2 (LT) (B8 1 , NiAs-type hexagonal), Cu 3 Al 2 (rhombohedral), Cu 9 Al 4 (HT) (c 0 , D8 2 , Cu 5 Zn 8 -type cubic), Cu 9 Al 4 (LT) (c 1 , D8 3 , Cu 9 Al 4 -type cubic), and Cu 3 Al (b, bcc). The Al-Zn phase diagram [1993Che] contains no intermediate phases. A miscibility gap occurs in the Al-based face centered cubic (fcc) solid solution below 351°C, where the fcc phase splits into fcc 1 and fcc 2 . The monotectoid reaction fcc 2 M fcc 1 + (Zn) follows at 277°C. The Cu-Zn phase diagram [1993Kow, Massalski2] is characterized by a series of peritectic reactions, which yield CuZn (b, bcc), Cu 5 Zn 8 (c, D8 2 -type cubic), CuZn 3 (d, B2, CsCl-type cubic), and CuZn 4 (e, cph). Zn (cph) has a c/a axial ratio much larger than e and the two coexisting cph phases are modeled separately with different interaction parameters [1993Kow]. The b phase orders to a CsCl-type B2 phase (b¢) through a second-order transition below $460°C. Ternary PhasesA ternary phase with rhombohedral symmetry and with the nominal composition Al 4 Cu 3 Zn (denoted s) is known in this system [Pearson3]. The homogeneity range of s and its temperature dependence are not clearly defined. The structurally-related, low-temperature form s¢ was found to be stable by [2005Hao] between 400°C and room temperature. Ternary Phase EquilibriaWith starting metals of 99.999% purity, [2009Ren] prepared diffusion couples of Cu-Zn master alloys with pure Al. The diffusion couples were annealed at 360°C for 48 h and quenched in water. The coexisting phase compositions were measured by electron probe microanalysis and listed. The isothermal section at 360°C constructed by [2009Ren] is shown in Fig. 1. In the Al-Zn system, the miscibility gap in the fcc phase closes at 351°C. The addition of Cu stabilizes this gap, which is stable at 360°C, even with as low as 0.1 at.% addition of Cu. The gap increases in width with increasing Cu content. In an earlier study, [2004Ren] determined tie-lines between fcc 1 and fcc 2 at 340 and 320°C for small additions of Cu and these are shown in Fig. 2. The Cu addition shifts the fcc 1 /(fcc 1 + fcc 2 ) and (fcc 1 + fcc 2 )/fcc 2 phase boundaries towards the Al-rich corner. Also, Cu segregates in the fcc 2 phase in preference to fcc 1 .The computed results of [2009Dai] indicate that the stabilizing effect of Cu on the Al-Zn miscibility gap increases with increasing Cu content, culminating in a metastable miscibility gap in the Al-Cu binary system...

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Effect of Ag addition to Zn–12Al alloy on kinetics of growth of intermediate phases on Cu substrate

Gancarz

Pstruś

Fima

et al. 2014

Journal of Alloys and Compounds

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Thermodynamic calculation on the miscibility gap of fcc-Al based solid solution in the Al–Zn–Cu system

Cited by 5 publications

References 3 publications

Analysis of Spinodal Decomposition in Al-Zn and Al-Zn-Cu Alloys Using the Nonlinear Cahn-Hilliard Equation

Analysis of Spinodal Decomposition in Al-Zn and Al-Zn-Cu Alloys Using the Nonlinear Cahn-Hilliard Equation

Al-Cu-Zn (Aluminum-Copper-Zinc)

Effect of Ag addition to Zn–12Al alloy on kinetics of growth of intermediate phases on Cu substrate

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