Key Takeaways & Executive Findings
- •• Coupled lattice Boltzmann and phase-field model accurately simulates dendritic growth under combined natural and forced convection in thin-walled Al-Cu alloys. • Convection breaks dendritic symmetry: equiaxed crystals show solute plumes and asymmetric arms, while columnar dendrites exhibit an optimal applied force for refined microstructure. • Forced convection consistently reduces the inclination angle of primary dendrites, offering a control lever for CGC process optimization. • Findings provide validated theoretical guidance for improving counter-gravity casting of thin-walled aerospace components.
Abstract
Thin-walled aluminum alloys, prized for their high specific strength, are critical to modern aerospace and other advanced industries. Counter-gravity casting (CGC) is a premier method for fabricating such components, where precise control over solidification microstructure is paramount. However, this control is challenged by the complex interplay of forced and natural convection during solidification. This study employs a coupled multiple-relaxation-time lattice Boltzmann (D2Q9) and quantitative phase-field model to simulate dendritic growth in a thin-walled Al-0.576wt.%Cu alloy. Simulations reveal that convection disrupts dendritic symmetry: for equiaxed crystals, solute plumes and asymmetric arm growth are observed, while for columnar dendrites, an optimal applied force exists that refines the microstructure without compromising economic viability. Furthermore, forced convection consistently reduces the inclination angle of primary dendrites. These findings, validated against experimental data, elucidate the micro-mechanisms of dendritic growth under convection, providing critical theoretical guidance for optimizing CGC processes.
1. Introduction
As industries advance, the demand for lightweighting has been steadily increasing in various industry sectors, particularly within the aerospace industry. Accordingly, thin-walled structures have become widely used in multiple aerospace components, including aerospace engines [1]. However, traditional gravity casting (GC) techniques often lead to defects such as incomplete filling, inclusions, shrinkage porosity/cavities within thin-walled castings, resulting from uncontrollable natural convections [1]. These conventional methods face even greater difficulties in producing high-quality and complex-shaped thin-walled castings.
In recent years, the emergence and development of counter-gravity casting (CGC) technology have proven its ability in manufacturing complex and thin-walled components [2]. Such technology has found widespread applications in various industry sectors, including aerospace [1], automotive manufacturing [3, 4], and electronics [5]. Nowadays, the primary categories of CGC techniques include low-pressure casting (LPC) [6], counter-pressure casting (CPC) [7], vacuum suction casting (VSC) [8], and adjusted pressure casting (APC) [9]. Unlike the GC process, the CGC process involves the molten metal being subjected to an artificially applied force in the direction opposite to gravity, in addition to the gravitational force. As a result, in the CGC process, the filling speed of the melt is more stable and controllable, resulting in higher-quality castings that are virtually free of defects such as inclusions, oxides, shrinkage porosity, and cavities. However, the solidification micro-mechanisms of thin-walled alloys still require in-depth investigation, and a quantitative description of the solidification microstructure in this process is essential.
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Jia-tuo An, Da-fan Du, Li-jun Zhang, An-ping Dong, Bao-de Sun (2026). Effects of natural and forced convections on dendritic growth in thin-walled Al-Cu alloy by counter-gravity casting: A phase-field lattice-Boltzmann study. China Foundry. https://doi.org/10.1007/s41230-026-5208-0
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Frequently Asked Questions
What is the main objective of this study?
The study aims to quantitatively investigate the effects of natural and forced convection on dendritic growth in thin-walled Al-Cu alloy during counter-gravity casting, using a coupled lattice Boltzmann and phase-field model.
What method was used in this research?
A coupled multiple-relaxation-time lattice Boltzmann (D2Q9) and quantitative phase-field model was employed to simulate dendritic growth in a thin-walled Al-0.576wt.%Cu alloy.
What are the key findings regarding convection effects?
Convection disrupts dendritic symmetry: equiaxed crystals show solute plumes and asymmetric arm growth, while columnar dendrites exhibit an optimal applied force that refines the microstructure. Forced convection consistently reduces the inclination angle of primary dendrites.
How were the simulation results validated?
The findings were validated against experimental data, confirming the accuracy of the model in predicting dendritic growth under convection.
What is the practical significance of this study?
The study provides critical theoretical guidance for optimizing counter-gravity casting processes, particularly for producing high-quality thin-walled aluminum alloy components in aerospace and other advanced industries.
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