This section deals with a common problem arising during para-equilibrium calculation:

Follow this example in which we try to estimate the amount of cementite forming in paraequilibrium with ferrite:

WHICH MODULE ? mu
MULTIPHASE OPTION ? def sy 'Fe,Mn,Cu,C' sou plus !
MULTIPHASE OPTION ? cl ab p(*) no p(BCC_A2,cementite) !
MULTIPHASE OPTION ? set temp 773 !
MULTIPHASE OPTION ? set w 100 !
MULTIPHASE OPTION ? set w( ) undef 2.0 0.5 0.2 !
MULTIPHASE OPTION ? cl para comp(Fe,Mn,Cu) !
MULTIPHASE OPTION ? co pri ea_st_re !

At this point, MTDATA complains. This is because you are trying to force the ratio of Cu/Fe and Mn/Fe to be identical in ferrite and cementite, but the model for cementite does not allow for copper.
Try again with:

MULTIPHASE OPTION ? cl no comp(Cu) !
MULTIPHASE OPTION ? co pri ea_st_re !

Always check that the different phases involved in a para-equilibrium calculation can include all the elements you classify as para.


PT-group 2003 Thomas Sourmail, Cambridge. Please email feedback !