Al-Mg COST 507 Thermochemical database for light metal alloys

Abstract

Bearing in mind the alloy categories defined by industrial partners at the beginning of the Action, a matrix was drawn up to define the binary systems forming the building blocks for the evaluation of higher-order systems. These binaries were then allocated to the different partners in Group C for evaluation. All partners made use of the selected data for the elements published by A.T. Dinsdale ' on behalf of SGTE. There was also agreement amongst partners with respect to the modelling of particular phases so that consistency could be maintained on proceeding from binary to higher-order systems combining evaluations originating from different laboratories. All results were prepared in exactly the same format to facilitate exchange of data and to provide a standard format for computer storage of the data by the database manager, Dr.Ansara, in Grenoble. Evaluations to produce optimized sets of coefficients were carried out using one or both of the two programs Bingss/Tergss written by Lukas 2 and Parrot developped by Jansson 3 contained in the Thermo-Calc databank system 4. These programs make use of experimental thermodynamic and phase diagram data, which are fed in as measured values with error limits. Using defined models for the different phases of the systems concerned, optimized coefficients are produced which permit a self-consistent description of the thermodynamic properties and the phase boundaries of the alloys. For some alloy systems the available experimental information is very scarce or unreliable. In such cases, only a part of the system may have been dealt with. In other cases, recourse may have had to be made to estimation procedures to obtain input data for the optimization process. The accuracy of the calculations involving these data will consequently be reduced. The following pages present in summarized form a complete description of the evaluation work carried out by the partners in Coordination Group C during the course of Round 1 and 2 of COST 507. The brief reports for each system contain a calculated phase diagram, information on the structures of the phases in the system. The thermodynamic coefficients used to produce the calculated information are also given.