MICRESS Forum

Hi MICRESS forum,

How do I access the data for the entropies of transformation, ds, and slopes of the equilibrium line ,m? I can't find a way using MicPad. Any help would be much appreciated.

Many thanks,
Matthew

Dear Matthew,

Those data is needed for description of the thermodynamic behaviour of the alloy you want to simulate. The easiest approach is if you have access to a corresponding database or to published Calphad descriptions. Then, using coupling to database via the TQ-interface is always the best option. You do not have to care for explicit values of thermodynamic data because they are used implicitly. Of course, it nevertheless is always recommended to monitor the data (in the .log and the .TabLin files) to check the reasonabiity of the data and/or their numerical treatment within MICRESS and the TQ-interface.

Otherwise, if you do not have a database (or a published .tdb-file) available, you have to take the information from literature, e.g. from phase diagram plots. Getting reasonable values for dS is especially challenging, because what you need is not exactly the transformation entropy but rather the derivative of the driving force with temperature. However, in case of solidification, dS is typically close to 1.0 J/(cm3K).

MICpad is an editor for MICRESS driving files. However, it is not a database for thermodynamic data, although it has some functionality for visualizing such data. An option to get some idea of thermodynamic data is to check existing MICRESS input files of simulation results (.log, .TabLin) where you also can access data for dS and m1/m2 for those systems and conditions. However, you should be careful because those data differ a lot depending on where (at which temperature and for which local compositions) they have been optained. But in principle, you can use a full dataset of linearisation data from the results of TQ-coupled MICRESS simulation as input phase diagram data (using linearTQ mode).

Bernd