Dendritic structure in unidirectionally solidified aluminum, tin, and zinc base binary alloys

Okamoto, Takuya; Kishitake, Katsuhiko

doi:10.1016/0022-0248(75)90217-1

Cited by 129 publications

(81 citation statements)

References 4 publications

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“…The experimental law represented by Eq. [3], which was proposed by Okamoto and Kishitake, [23] has also been included in Figure 13. It can be seen that these experimental laws do not represent the general tendency of the experimental results with an increasing Ni content, despite the reasonable agreement observed with the results of Al-1.0 and Al-2.5 wt pct Ni alloys.…”

Section: Methodsmentioning

confidence: 97%

“…[22] To date, the study by Okamoto and Kishitake [23] is the sole study available in the literature in which an experimental analysis of the dendritic growth in the transient solidification of Al-Ni hypoeutectic alloys was developed. The authors' samples were directionally solidified from bottom to top by dipping the bottom of the crucible in a metal bath.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Development in Al-Ni Alloys Directionally Solidified under Unsteady-State Conditions

Canté

Spinelli

Ferreira

et al. 2008

Metall Mater Trans A

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Three Al-Ni hypoeutectic alloys were directionally solidified under upward unsteady-state heatflow conditions. Primary (k 1 ) and secondary (k 2 ) dendrite arm spacings were measured along the castings for all alloys and correlated with transient solidification thermal variables. A combined theoretical and experimental approach was used to quantitatively determine such thermal variables, i.e., transient metal/mold heat-transfer coefficients, tip growth rates, thermal gradients, tip cooling rates, and local solidification time. The article also focuses on the dependence of dendrite arm spacings on the alloy solute content. Furthermore, the experimental data concerning the solidification of Al-1.0, 2.5, and 4.7 wt pct Ni alloys are compared with the main predictive dendritic models from the literature.

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Section: Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Microstructural Development in Al-Ni Alloys Directionally Solidified under Unsteady-State Conditions

Canté

Spinelli

Ferreira

et al. 2008

Metall Mater Trans A

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“…[29] Most of the results in the literature, concerning steady and unsteady regimes, pertaining to l 2 in hypoeutectic alloys, indicate a decrease in spacing with increasing cooling rate for a given alloy composition and with increasing solute content for a given cooling rate. [28,29,38,39] The reports in the literature also indicate that for steady or unsteady growth conditions, the primary arm spacings decrease as G L or V L increases. On the other hand, there has been some disagreement in the literature regarding the influence of the initial alloy composition on primary spacings.…”

mentioning

confidence: 84%

Heat flow parameters affecting dendrite spacings during unsteady-state solidification of Sn-Pb and Al-Cu alloys

Rocha

Siqueira

Garcia

2003

Metall Mater Trans A

158

108

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Solidification thermal parameters and dendrite arm spacings have been measured in hypoeutectic SnPb and Al-Cu alloys solidified under unsteady-state heat flow conditions. It was observed that both primary and secondary spacings decreased with increased solute content for Sn-Pb alloys. For Al-Cu alloys, the primary spacing was found to be independent of composition, and secondary spacings decrease as the solute content is increased. The predictive theoretical models for primary spacings existing in the literature did not generate the experimental observations concerning the Sn-Pb and AlCu alloys examined in the present study. The theoretical Bouchard-Kirkaldy's (BK's) equation relating secondary spacings with tip growth rate has generated adequately the experimental results for both metallic systems. The insertion of analytical expressions for tip growth rate and cooling rate into the predictive model, or into the resulting experimental equations in order to establish empirical formulas permitting primary and secondary dendritic spacings to be determined as functions of unsteadystate solidification parameters such as melt superheat, type of mold, and transient metal/mold heattransfer coefficient is proposed.for instance, the solidification conditions of a body of irregular shape, these variables are interdependent, cannot be controlled, and vary freely with time. The analysis of dendritic structures in the unsteady-state regime is very important, since it encompasses the majority of industrial solidification processes.The measurements of primary and secondary dendrite arm spacings involve looking at the microstructure after complete solidification. Primary spacings do not coarsen with time and can be accurately measured from the microstructure and compared with growth models. On the other hand, secondary spacings are seen to rapidly coarsen during solidification, and the effect of coarsening has to be taken into account by the predictive growth models. [29] Most of the results in the literature, concerning steady and unsteady regimes, pertaining to l 2 in hypoeutectic alloys, indicate a decrease in spacing with increasing cooling rate for a given alloy composition and with increasing solute content for a given cooling rate. [28,29,38,39] The reports in the literature also indicate that for steady or unsteady growth conditions, the primary arm spacings decrease as G L or V L increases. On the other hand, there has been some disagreement in the literature regarding the influence of the initial alloy composition on primary spacings. It has been reported in the majority of cases that l 1 increases as C 0 (for hypoeutetic alloys) increases for both steady and unsteady growth conditions. [28,29] However, Sharp and Hellawell [44] found that C 0 has little effect on primary spacings and Spittle and Lloyd [46] reported that for steady-state growth with low G L , l 1 decreased as C 0 increased and was independent of C 0 for high G L , and for unsteady solidification l 1 decreased as C 0 increased.The present article focuse...

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“…As the fluid flow in the interdendritic channels depends on these dendrite arm spacings, it is important to know the variation of these parameters during the solidification process to analyze microsegregation pattern which influences for instance the homogenization kinetics, ultimate tensile strength, ductility, toughness and yield tensile strenght of solidified alloys [12][13] . It is well known that dendrite fineness can be of even more importance than the grain size for the improvement of mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Al-3wt.%Si alloy in unsteady-state horizontal directional solidification

et al. 2013

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The main purpose of this paper is to investigate both the columnar to equiaxed transition and primary dendritic arm spacings of Al-3wt.%Si alloy during the horizontal directional solidification. The transient heat transfer coefficient at the metal-mold interface is calculated based on comparisons between the experimental thermal profiles in castings and the simulations provided by a finite difference heat flow program. Simulated curve of the interfacial heat transfer coefficient was used in another numerical solidification model to determine theoretical values of tip growth rates, cooling rates and thermal gradients that are associated with both columnar to equiaxed transition and primary dendritic arm spacings. A good agreement was observed between the experimental values of these thermal variables and those numerically simulated for the alloy examined. A comparative analysis is carried out between the experimental data of this work and theoretical models from the literature that have been proposed to predict the primary dendritic spacings. In this context, this study may contribute to the understanding of how to manage solidification operational parameters aiming at designing the microstructure of Al-Si alloys.

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Dendritic structure in unidirectionally solidified aluminum, tin, and zinc base binary alloys

Cited by 129 publications

References 4 publications

Microstructural Development in Al-Ni Alloys Directionally Solidified under Unsteady-State Conditions

Microstructural Development in Al-Ni Alloys Directionally Solidified under Unsteady-State Conditions

Heat flow parameters affecting dendrite spacings during unsteady-state solidification of Sn-Pb and Al-Cu alloys

Characterization of the Al-3wt.%Si alloy in unsteady-state horizontal directional solidification

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