Phase diagram evaluations and applications in light metal alloys

Sammanfattning: A thermodynamic database for light alloys have been assessedusing the CALPHAD method. The database contains a newevaluation of aluminium rich alloys containing Fe, Mn and Si,and it may be used also for alloys containing small amounts ofMg. The four component database for Al-Fe-Mn-Si is based onrecent evaluations of all the binary and ternary subsystems.The assessments of Al-Mn, Al-Fe-Mn and the quaternary systemare reported in the present work.The thermodynamic database consists of functions describinghow the Gibbs energy depends on temperature and composition inall phases of the systems. These functions are modelled usingthe Compound Energy Formalism. The model parameters are fittedto all available experimental thermochemical and phase diagraminformation. Phases with an order-disorder transition areimportant in many alloy systems. This phenomenon is modelledusing the Compound Energy Formalism.Several calculated phase diagrams are presented, which showthat the experimental information is well described by thecalculations, and indicates that the database can be used topredict phase equilibria in real systems.The database is also used for solidification simulation inaluminium alloys using theScheil-Gulliver model. This simplemodel, which requires only thermodynamic data, isdemonstratedto produce good results. The solidification model isimplemented inThermo-Calc, a general software for thermodynamiccalculation.KEYWORDS:Phase Diagrams, Thermodynamics, Aluminium,Iron, Manganese, Silicon, Modelling, Compound Energy Formalism,Chemical Ordering, Solidification.