Thermochemical and Constitutional Properties of Al-Si-Mg-Cu Alloys

• Applicant: Professor Dr.-Ing. Rainer Schmid-Fetzer
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: from 2010 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 138384390

The global goal of this particular project- set in the initial proposal for the entire funding period - remains the systematic research aiming at the determination of thermochemical and constitutional properties for pertinent alloys of the Al-Si-Mg-Cu system. Dedicated experimental investigations on key alloy samples, selected by progressively advancing thermodynamic calculations in these systems are employed. This combination of Calphad-type calculations with selected experiments will be decisive for the final Calphad-type thermodynamic modelling with a consistent description of both the thermochemical properties and the entire phase diagram with highest precision. Providing these directly determined materials data is essential to the overall goal of understanding technologically relevant solidification of aluminium alloys quantitatively and reduces the inherent ambiguity in solidification models in which these properties are often misused as fitting parameters.In the proposed period the work will focus on the Cu-Si binary and the Al-Cu-Si ternary system and selected quaternary data. Jointly with the project “Thermodynamic evaluation of phase diagrams", a replacement of the preliminary thermodynamic description, based only on data available in the literature, is aimed at, combining the new experimental results and the ab initio energy calculations from “Ab initio prediction of thermodynamic data”. The quaternary Q phase and its phase equilibria will be investigated in more detail. After the complex preparation of Q as a single phase was achieved for the first time in close cooperation with “Critical solidification experiments” in the first round, the key thermodynamic data (heat of fusion resp. quaternary decomposition reaction and associated temperatures, as well as heat capacity as function of temperature) will be determined. To this purpose a spectrum of sophisticated laboratory equipment, specifically designed for high precision experimental investigation of thermodynamic and constitutional alloy properties is available.

• DFG Programme: Research Grants