Solidification and Structural Characteristics of &amp;alpha;(Al)&amp;ndash;Mg&lt;SUB&gt;2&lt;/SUB&gt;Si Eutectic

Li, Shunpu; Zhao, Shengxu; Pan, M. X.; Zhao, D.Q.; Chen, Xichen; Barabash, O.M.; Barabash, Rozaliya

doi:10.2320/matertrans1989.38.553

Cited by 47 publications

(18 citation statements)

References 11 publications

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“…Resulting values of K LSW and K GBD are, respectively, factors of 2 to 4 ϫ 10 3 and 3 ϫ 10 5 below their corresponding values obtained experimentally (Table I), indicating that neither solute diffusion through the ␣-Al crystal lattice nor along its grain boundaries can account for the observed rates of coarsening of Mg 2 Si in this alloy at 590 °C. A further possibility arises from the proximity of 590 °C to the solidus temperature (ϳ620 °C according to the phase diagram "typical" [5] 0.28 [6] Mg 38.3 2.0 ϫ 10 Ϫ5 1.0 [7] of a 6XXX alloy reproduced by the authors in their article), and the authors' own suggestion that the "classical phase diagram" may be in error. Let us suppose that 590 °C is sufficiently high to cause at least partial melting,* which will *Bäckerud et al [12] report solidification reactions down to 531/536 °C for 6030 and 6351 alloys, which straddle the composition of 6105.…”

Section: H Jonesmentioning

confidence: 99%

Discussion of “the effect of heat treatment on Mg2Si coarsening in aluminum 6105 alloy”

Jones

2005

Metall Mater Trans A

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This interesting article [1] includes measurements of the size distribution, average radius , and volume fraction f of globular Mg 2 Si particles in this Al-Mg-Si alloy vs duration of homogenization treatment for up to 7 days at 590 °C. The authors conclude, on the basis of regression analysis, that the results show a particularly strong correlation with n ϭ 3.8 in [1] where t is time at temperature and is the value of at t ϭ 0, suggesting that grain boundary diffusion (n ϭ 4) dominates volume diffusion (n ϭ 3) in the coarsening of these particles. The present purpose is to offer an alternative interpretation of these results.The experimental data at issue are presented in Table I, together with resulting values of and for each value of t, taking at t ϭ 0. These results give mean K values of 3.6 Ϯ 0.4 ϫ 10 Ϫ20 m 3 /s for volume diffusion and 8.3 Ϯ 0.7 ϫ 10 Ϫ25 m 4 /s for grain boundary diffusion control. Table II presents corresponding values of K predicted from the LSW [2,3] and Kirchner [4] models, respectively:and [3] where C ∞ is solid solubility of the controlling solute; D and DЈ are its diffusivities in the matrix and along grain boundaries; w is grain boundary width; ␥ is dispersoid/matrix interfacial energy; ⍀ is the volume per mol of dispersoid containing one atom of controlling solute; R is the gas constant; T is the temperature (here 863 K); A ϭ (2/3-m ϩ m 3 /3), where m is half the ratio of grain boundary energy to particle/matrix interfacial energy; and B ϭ 0.5 ln (1/f ), where f is the average area fraction occupied by a particle on the grain boundary. Resulting values of K LSW and K GBD are, respectively, factors of 2 to 4 ϫ 10 3 and 3 ϫ 10 5 below their corresponding values obtained experimentally (Table I), indicating that neither solute diffusion through the ␣-Al crystal lattice nor along its grain boundaries can account for the observed rates of coarsening of Mg 2 Si in this alloy at 590 °C. A further possibility arises from the proximity of 590 °C to the solidus temperature (ϳ620 °C according to the phase diagram "typical"Table I. Results from Reference 1 for Mean Radius r vs Time t at 590 °C for Mg 2 Si Particles in 6105 Aluminum Alloy t (days) 0 1 2 3 4 5 6 10.0 16.6 19.8 22.2 23.6 24.1 26.3 K 1 (m 3 /s) -0.041 0.039 0.038 0.035 0.030 0.033 mean 0.036 Ϯ 0.004 m 3 /s K 2 (m 4 /s) -0.76 0.83 0.90 0.87 0.76 0.90 mean 0.83 Ϯ 0.07 m 4 /s Here, and with . r o ϭ 10 mm K 2 ϭ (r 4 Ϫ r 4 )/t K 1 ϭ (r 3 Ϫ r 3 )/t r (mm)

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Section: H Jonesmentioning

confidence: 99%

Discussion of “the effect of heat treatment on Mg2Si coarsening in aluminum 6105 alloy”

Jones

2005

Metall Mater Trans A

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“…The temperature gradient can then influence the eutectic spacings. The influence of temperature gradient on the eutectic spacings was investigated by several authors [28][29][30][31][32]. The variations of rod spacings ( T , L and e ) with temperature gradient (G) at a constant V (6.80 m/s) are given in Table 1 and shown in Fig.…”

Section: The Effect Of Temperature Gradient On the Rod Spacingsmentioning

confidence: 99%

Experimental investigation of the effect of solidification processing parameters on the rod spacings in the Sn–1.2wt.% Cu alloy

Çadırlı

Böyük

Engin

et al. 2009

Journal of Alloys and Compounds

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“…However, it should be noted that the effect of tem- perature gradient (G) on lamellar spacing (λ) cannot be ignored. Several authors have reported that the influence of temperature gradient on lamellar spacing [13][14][15][16]. The research of Ç adırlı et al [16] indicates that an increase in temperature gradient leads to decrease in lamellar spacing for a given constant solidification rate, and λ and G have the relationship of λ = kG −0.37 L .…”

Section: Resultsmentioning

confidence: 98%

Growth characteristic of Al2O3/Y3Al5O12 (YAG) eutectic ceramic in situ composites by laser rapid solidification

Zhang

Cui

et al. 2008

Journal of Alloys and Compounds

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Solidification and Structural Characteristics of α(Al)–Mg<SUB>2</SUB>Si Eutectic

Cited by 47 publications

References 11 publications

Discussion of “the effect of heat treatment on Mg2Si coarsening in aluminum 6105 alloy”

Discussion of “the effect of heat treatment on Mg2Si coarsening in aluminum 6105 alloy”

Experimental investigation of the effect of solidification processing parameters on the rod spacings in the Sn–1.2wt.% Cu alloy

Growth characteristic of Al2O3/Y3Al5O12 (YAG) eutectic ceramic in situ composites by laser rapid solidification

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