Abstract:

Truly multicomponent and multiphase materials emerged in the focus of quantitative thermodynamic descriptions using the Calphad method in recent years. A great variety of applications of such consistent Calphad-generated databases has been successfully documented in the field of Computational Thermodynamics. These comprise focused alloy development as well as materials processing, such as solidification, heat treatment and forming. Selected examples of our work in this field will be given with emphasis on applications to magnesium alloys.

The applications focus on these examples:

-- Mg-Al-Zn-Mn (AZ and AM alloy series, real solidus and liquidus)
　　-- Mg-Al-Sr-Ca-Mn (AJ, AX and AXJM advanced alloy series)
　　-- Mg-Zn-RE (ZE) alloys and Mg-RE'-RE" alloys

Microstructures of Mg-Zn-Ce (ZE) alloys support the thermodynamic calculations shown in the phase diagram section at constant 85 at.% Mg.

Topic2: Computational Thermodynamics and the Calphad Method: The Basics

A basic overview and introduction is given for the following methods and tools:

• Calphad Method, which aims at the generation of a thermodynamic description using all available experimental & theoretical data for a consistent modeling of thermodynamics and constitution

• Computational Thermodynamics, which involves the application of "Calphad-generated" databases in Materials Science & Engineering, specifically for multicomponent and multiphase material systems

We will go through a brief summary of thermodynamic software, data & databases, especially for light alloys. Inherent problems in the classical approach of reaction equations (example SiO2 + 2 C = ?) will be elucidated by global chemical equilibrium calculations. Solidification of multicomponent alloys can be quantitatively treated by the two extreme models (Equilibrium and Scheil) without knowing any kinetic material parameters and this will be detailed for the example of Mg-Al-Zn alloys. Finally, an application to the solidification behavior of monotectic ternary Al-alloys will be given.

CV-R. Schmid-Fetzer