Structural and Chemical Atomic Complexity


Bengt Hallstedt © Copyright: IWM


Bengt Hallstedt

Research field Development Tool Materials


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Structural and Chemical Atomic Complexity: From Defect Phase Diagrams to Material Properties; Part project C06, Thermodynamic Modeling in Mg-Al-Ca


In this project, a completely new 3rd generation Calphad description for the Mg-Al-Ca system will be developed, which will describe all important phases over the complete concentration range and from 0 K to well above melting temperatures. This will be possible by basing the modeling on ab initio calculations and by using new models for the elements currently under development under the auspices of SGTE (Scientific Group Thermodata Europe). While knowledge about the phase diagram and the thermodynamic properties of its (bulk) phases is necessary for the development and processing of alloys, many of their properties are determined by defects, in particular grain boundaries, phase interfaces and dislocations. However, the thermodynamic properties of defects and their transitions between different states (or phases) are much less understood. A central theme within the SFB is the development of defect phase diagrams, i.e. the investigations of transitions between different defect phases. In this project, thermodynamic models for different defect phases will be developed, which can be used to calculate equilibria between different phases in order to build defect phase diagrams. In addition a framework for the inclusion of composition and temperature dependent crystal dimensional (lattice parameters and angles) and elastic constants will be developed.


  • Development of an accurate and complete thermodynamic description of the Mg-Al-Ca system
  • Descriptions of crystal dimensions and elastic properties
  • Exploration of defect phase diagrams

Project Contents

  • Thermodynamic modelling of the Mg-Al-Ca ternary system and its binary subsystems using 3rd generation Calphad models
  • Modelling of crystal structure data (lattice parameters, molar volumes) as function of temperature and composition
  • Modelling of elastic properties (elastic constants, bulk modulus, Young’s modulus, shear modulus) as function of temperature and composition
  • Development of concepts and models for dislocations, grain boundaries and phase interfaces as defect phases

Project Partners

IMM, AICES, MCh, IEHK, GfE, IBF, KKS, MPIE Düsseldorf, FAU Erlangen

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Grant number: 409476157