Modeling Dissolution in Aluminium Alloys Using a Sharp-Interface Front-Tracking Method

Abstract

Aluminum alloy microstructures are highly segregated upon solidification. The alloy may then be exposed to various thermal and mechanical treatments to homogenize the microstructure. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. The dissolution of these soluble phases and diffusion of solute out into the aluminum matrix is important to the final strength of the alloy. A new algorithm has recently been developed [1] for solving secondary phase dissolution in aluminum alloys. Dissolution is treated as a diffusion-limited moving-boundary phase-change problem. The immersed-boundary front-tracking method of Juric and Shin [2] has been altered to incorporate some aspects of the ghost-fluid method. This new algorithm, termed the method is applied to dissolution of secondary phases in dilute multi-component aluminum alloys in one and two dimensions. The sharp-interface method is shown to agree well with the dissolution behavior of precipitates in aluminum alloys when compared to published experimental results. Additionally, the sharp-interface method is shown to perform better than similar models found in the literature.