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sundmanbo / opencalphad

Open Calphad, thermodynamic calculation code
http://www.opencalphad.org
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Calculation of a surrounded single in a diagram. #44

Closed Ebert-Daniel closed 4 years ago

Ebert-Daniel commented 4 years ago

Dear Professor Bo,

I'm trying to calculate the FeTi phase diagram using the TDB attached. The single phase region appears to be "neglected" even when I set a start equilibrium inside the single phase field and map it separately. I calculated it with our "favorite" thermodynamic software to confirm that we have this phase region. I'm sending both results attached. Would you suggest any way for calculating it with OC?
I wish you all the best and thank you for your hard work for providing a free software for materials thermodynamics

Best wishes EA

feti.txt feti_bo-phdia_OC.pdf Fe-Ti (TC_calc)- feti_bo

sundmanbo commented 4 years ago

Hi EA

The problem is easy to solve, in your TDB file you must add that the BCC_B2 phase is magnetic. In TC that is set automatically when the BCC_A2 is magnetic but in OC the treatment of "disordered fraction sets" is different. Thus add a line TYPE_DEFINITION M GES A_P_D BCC_B2 MAGNETIC -1.0 4.00000E-01 ! and add M to the line PHASE BCC_B2 %/M .....

Mapping in OC is sensitive to the start point, best to start at x(ti)=.7 and T=1000 in the miscibility gap for BCC. You will also need a separate start point to calculate the gamma loop.

Best wishes

Bo