Modeling Dendrite Coarsening and Remelting during Directional Solidification of Al-06wt.%Cu Alloy

Sari, Ibrahim; Alrasheedi, Nashmi; Ahmadein, Mahmoud; Djuansjah, Joy; Hachani, Lakhdar; Zaidat, Kader; Wu, Menghuai; Kharicha, Abdellah

doi:10.3390/ma17040912

Cited by 3 publications

(2 citation statements)

References 20 publications

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“…The predictions were found to be in good agreement with the experimental λ 2 scatters for all the Al-Cu-Si alloys examined, with a slight tendency to overestimate the λ 2 values for the only Al-Cu-Mg alloy cast. Sari et al [22] proposed a model able to tackle the growth and the coarsening of secondary side dendrite arms with only two adjacent side arms in concurrence. Their model was applied to directional solidification of an Al-06 wt%Cu alloy in a Bridgman experiment.…”

Section: Introductionmentioning

confidence: 99%

Prediction of the Secondary Arms Spacing Based on Dendrite Tip Kinetics and Cooling Rate

Sari,

Ahmadein,

Ataya

et al. 2024

Materials

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Secondary dendrite arm spacing (SDAS) is one of the most important factors affecting macrosegregation and mechanical properties in solidification processes. Predicting SDAS is one of the major parameters in foundry technology. In order to predict the evolution of microstructures during the solidification process, we proposed a simple model which predicted the secondary dendrite arm spacing based solely on the tip velocity (related to the tip supersaturation) and cooling rate. The model consisted of a growing cylinder inside a liquid cylindrical envelope. Two important hypotheses were made: (1) Initially the cylinder radius was assumed to equal the dendrite tip radius and (2) the cylindrical envelope had a fixed radius in the order of the dendrite tip diffusion length. The numerical model was tested against experiments using various Pb–Sn alloys for a fixed temperature gradient. The results were found to be in excellent agreement with experimental measurements in terms of SDAS and dendrite tip velocity prediction. This simple model is naturally destined to be implemented as a sub-grid model in volume-averaging models to predict the local microstructure, which in turn directly controls the mushy zone permeability and macrosegregation phenomena.

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Section: Introductionmentioning

confidence: 99%

Prediction of the Secondary Arms Spacing Based on Dendrite Tip Kinetics and Cooling Rate

Sari,

Ahmadein,

Ataya

et al. 2024

Materials

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“…This new approximation was in good agreement with the Ivantsov function for a wide range of supersaturation values. In addition, Sari et al [ 29 ] proposed an innovative model for precisely predicting secondary dendrite arm spacing (SDAS) based on the tip velocity and cooling rate during the directional solidification of various Pb-Sn alloys. This model conceptualized a growing cylinder within a liquid cylindrical envelope.…”

Section: Introductionmentioning

confidence: 99%

A Study on Ammonium Chloride Dendrite Tip Kinetics: The Importance of the Solid–Liquid Density Change and Interfacial Kinetics

Alrasheedi,

Stefan-Kharicha,

Sari

et al. 2024

Materials

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Ammonium chloride (NH4Cl) has been extensively studied as a transparent analogue for investigating the solidification of metals due to its distinctive properties and the simplicity of the experimentation. Furthermore, NH4Cl exhibits a striking resemblance in solidification behavior to the majority of binary eutectic alloy systems, rendering it a valuable model for studying phase transition phenomena. Experiments conducted on ammonium chloride are frequently employed to validate numerical models for predicting grain structures, macrosegregation, and the columnar-to-equiaxed transition (CET). This latter phenomenon arises due to differences in the velocities of columnar dendrite tips and the liquidus isosurface. However, the kinetics of dendrite tip growth, as a function of supersaturation, remains poorly understood for this commonly used alloy. The objective of this study was to utilize the available experimental data in conjunction with Ivantsov correlations to shed light on the ambiguous kinetics. The results indicate that when considering the crystal–melt density ratio, the Ivantsov solution offers a good correlation. Furthermore, incorporating a moderate interfacial kinetic coefficient enhances the correlations further. This correlation can be implemented in numerical models, which will aid in the determination of the columnar front, the columnar-to-equiaxed transition, and the equiaxed growth velocities.

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Effect of Marangoni flow during the solidification of a Fe-0.82wt.%C steel alloy

Sari,

Andreas Ludwig,

Kharicha

2024

J. Phys.: Conf. Ser.

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A two-phase Mixture model is proposed to simulate the liquid-solid phase transition of a Fe-0.82wt%C steel alloy under the effect of Marangoni flow. This model simplifies computations by solving a single momentum and enthalpy equation for the mixture phase using a three-dimensional finite volume method. The simulation involves solidifying a rectangular ingot (100 × 10 × 100 mm3) from the cold bottom surface towards the hot-free surface at the top. To facilitate heat exchange with the surrounding environment, a high heat transfer coefficient of h = 600 W/m2/K was applied on the bottom surface to establish an upward solidification direction. However, a lower heat transfer coefficient of 20 W/m2/K was applied on the top free surface, which was considered flat. This study aims to examine the effect of Marangoni flow generated by surface tension on flow and segregation patterns. The results show that the Marangoni flow emerges at the free surface and penetrates into the liquid depth, leading to the formation of hexagonal patterns along the liquid thickness. Upon full solidification, macro-segregation also exhibits hexagonal structures, mirroring the stationary hexagonal shapes generated by Marangoni flow.

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Modeling Dendrite Coarsening and Remelting during Directional Solidification of Al-06wt.%Cu Alloy

Cited by 3 publications

References 20 publications

Prediction of the Secondary Arms Spacing Based on Dendrite Tip Kinetics and Cooling Rate

Prediction of the Secondary Arms Spacing Based on Dendrite Tip Kinetics and Cooling Rate

A Study on Ammonium Chloride Dendrite Tip Kinetics: The Importance of the Solid–Liquid Density Change and Interfacial Kinetics

Effect of Marangoni flow during the solidification of a Fe-0.82wt.%C steel alloy

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