An assessment of thermodynamic data for the liquid phase in the Al-rich corner of the Al-Cu-Si system and its applicatio
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Basic and Applied Research: Section I
An Assessment of Thermodynamic Data for the Liquid Phase in the Al-Rich Corner of the Al-Cu-Si System and Its Application to the Solidification of a 319 Alloy X.M. Pan, C. Lin, J.E. Morral, and H.D. Brody
(Submitted April 30, 2004; in revised form December 1, 2004) A thermodynamic database for the liquid phase in the Al-rich corner of the Al-Cu-Si system has been developed by fitting all thermodynamic and phase diagram information that is currently available from the literature. A comparison between the calculated results and the experimental data is presented, and the calculated results reproduce all the liquidus and solidus boundaries to within experimental scatter. Also, the present assessment was used to predict the solidification behavior of an Al-3.5wt.%Cu-7wt.%Si, 319-type alloy. Subsequent experimental results validate these predictions.
1. Introduction
2. Evaluation of Previous Work
The unique properties of Al make its alloys some of the most commercially important materials in modern industry. For example, Al-Cu-Si alloys are of interest for application in automotive and aerospace technology due to their quality and lightweight. Their corrosion resistance is superior to that of Al-Cu alloys, and their strength is better than that of Al-Si alloys. Therefore, a basic understanding of the thermodynamics, phase relationships, and solidification behavior of this alloy system will be useful for future work on Al-Cu-Si alloys and process design. Over the past several decades, much work has been done on this system, especially in the Al-rich corner. That work has laid a foundation for understanding the ternary system, but no thermodynamic assessment has been reported. The purpose of this work was to develop a thermodynamic description of the liquid phase in the Al-Cu-Si system to facilitate our further study of more complex Al-Cu-Si-X (X ⳱ Mg, Fe, Mn) multicomponent systems. Due to scarce experimental information away from the Al-rich corner, the present work will focus mainly on creating a database for the Al-rich corner. In the following sections, a brief introduction to the experimental information available from the literature is presented first. Then the thermodynamic models are discussed, and the thermodynamic parameters are evaluated. Third, calculations from the present thermodynamic description are discussed and compared with the experimental information. Finally, the solidification behavior of an Al-3.5wt.%Cu7wt.%Si, 319-type alloy that was studied experimentally will be compared with predictions made from the present assessed database.
2.1 Binary Subsystems
X.M. Pan, C. Lin, and H.D. Brody, Department of Metallurgy and Materials Engineering, University of Connecticut, Storrs, CT 062693136; and J.E. Morral, Materials Science and Engineering Department, The Ohio State University, Columbus, OH 43210. Contact e-mail: [email protected].
Complete assessments of the binary subsystems Al-Cu and Al-Si are available from the COST Action 507 [1998Gro, 1998Sau
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