What's New in Equilib |
What follows are summaries of the more important programming changes in Equilib that have appeared in: .
FactSage 6.1 (2009)
The numerical results of the calculations can be post-processed for plotting in the usual way. The following graph shows the 'fraction solid' plot including both the Scheil and the Equilibrium curve.
The results from the calculation may also be used in another way in order to keep track of the various phases which are formed in the different temperature ranges. In the Summary screen the phases listed in conjunction with the various constituents (phase assemblages) can be used as direct input for further equilibrium calculations. By pointing and clicking product phases can be recycled through the calculation. This is particularly useful when investigating the behaviour of castings of complex alloy systems. See also example #16 in the Advanced Equilib examples.
In the Equilib Results Window click on the XML Icon (or click on 'Output > Run Fact-XML ...'). Extensive changes and additions have been carried out, including
FactSage 6.2 (2010)
For example, in the FACT53 compound database the non-stoichiometric compound Fe(7.016)S(8) (e.g. 7.016 Fe, 8 S)
is identified by its nominal stoichiometric formula Fe7S8; Zn(2.001)Ca(0.9999) is Zn2Ca; Fe(10.99992)S(12) is Fe11S12; etc.
When such a compound (e.g. the nominal composition Fe7S8, Zn2Ca, Fe11S12, ...) is entered as a reactant it is 'flagged' by a yellow mask in the Reactants Window as being non-stoichiometric (for this to occur the 'initial conditions' box must be checked).
Sometimes a non-stoichiometric compound has more than one phase. For example, in the SGPS (SGTE) compound database, wustite Fe(0.947)O(1) has the nominal composition FeO and data are stored for both the solid and the gas phase.
But the stored composition for the gas phase is for the nominal composition (FeO) since a non-stoichiometric gas molecule cannot exist.
For a non-stoichiometric compound in Equilib and Phase Diagram
Most calculations with FToxid-SLAG use FToxid-SLAGA - this is the slag solution with all the oxides and includes up to 10% sulfur if this element is also included in the calculation.
The other slag phases are:
More extensive details on the FToxid-SLAGA, -SLAGB, etc. phases can be found in the Documentation
located in the FactSage Main Menu.
If 'I' is not selected and a calculated composition is within or near a miscibility gap,
then the composition will most likely be in error.
If 'I' is selected but there is no miscibility gap, the calculated composition will be correct but
the time to calculate will be increased.
In other words, selecting 'I' is a safe way but possibly time consuming especially when several phases are
incorrectly designated as 'I' when '+' would suffice.
In order to determine if option 'I' should be used it has been necessary to consult the documentation.
For example, in FToxid database the following phases may have regions of 2-phase or 3-phase immiscibility:
FToxid-SLAG, -mullite, -spinel, -monoxide, -pyroxenes, -olivine, -corundum, -ilmenite.
Prior to 6.2 such phases when selected were automatically set to option 'I'. But within a given solution, there will only be a miscibility gap when certain elements are present.
For example, in the FToxid-MeO monoxide phase that contains FeO, CaO, MgO, MnO, NiO, CoO, etc.
only those solutions containing CaO could have a miscibility gap.
In FactSage 6.2 the precise conditions for option 'I' are now stored within the FToxid, FTmisc (for sulphide systems) and FTsalt databases.
Equilib and Phase Diagram will automatically select option '+' when immiscibility is not possible, and set it to 'I' for those cases where option 'I' should be used.
It is no longer necessary to consult the documentation - the selection of '+' or 'I' will be done for you.
We consider this to be a very important and useful improvement to the Equilib and Phase Diagram modules.
Note: you are can overide the default 'I' setting by manually selecting '+' but this is not recommended.
In FToxid-SLAGA for example, this may result in Slag-liquid#1 appearing in the list at the top, far away from Slag-liquid#2 which would be at the bottom if it is not stable.
In FactSage 6.2 both immiscible phases for the same solution phase (e.g. Slag-liquid#1 and Slag-liquid#2)
will now appear together
- the position in the list is determined by the amount (or activity) of the more prominent immiscible phase.
A range of alpha (pressure, etc.) can be increasing, for example '0 1 0.2' (e.g. 0 0.2 0.4 ... 1),
or decreasing, for example ' 1 0 0.2' (e.g. 1 0.8 0.6 ... 0).
However the temperature range is an exception and has always been treated as increasing.
For example the temperature range '3000 1000 500' (e.g. 3000 2500 ... 1000) would be treated as
'1000 3000 500' (e.g. 1000 1500 ... 3000).
In FactSage 6.2 the temperature range may now be for heating
('1000 3000 500') or for cooling ('3000 1000 500')
and the output in the Results Windows respects the direction in temperature.
The cooling option is useful when identifying the first solids precipitated as shown next.
The Equilibrium 'transitions' button has been replaced by two buttons:
When a transitions button is pressed, a 'Transitions frame' is displayed
in the Menu Window and the 'number of transitions' can now be specified.
You can specify 'All' to list all the transitions (just as before), or you can limit the number of reported transitions to 1, 2, or 3 etc. as you wish.
When combined with the 'heating' or 'cooling' temperature range described earlier, this means that you need
only calculate the first 1, 2 or 3 etc. transitions on cooling down from a high temperature
(e.g. the liquidus for the first precipitate, etc.)
or the first 1, 2, or 3 etc. transitions on heating up from a low temperature.
FactSage 6.3 (2012)
Calculated activities (moles, mole fractions, grams and Wt.% - click on Show to specify)
are listed in the species Selection Window.
Several changes and additions have been carried out to the display.
The screenshot displays the Selection Window gas phase results
for the adiabatic reaction (Delta H = 0):
A total of 99 pages were calculated where <A> = 0.01, 0.2, 0.03 ... 0.99.
Page 50 shown here corresponds to <A> = 0.50.
For the case of CO2(g) (species 26) it is seen that the activity (e.g. partial pressure) = 3.6974e-2 atm when <A> = 0.5
and that P(max) is 0.1402 atm at page 79 (where <A> = 0.79).
It is seen that the maximum adiabatic temperature is 2784.71 C
at page 65 (e.g. <A> = 0.65).
FToxid-SLAGB with SO4; FToxid-SLAGC with PO4; FToxid-SLAGD with CO3;
FToxid-SLAGE with H2O/OH; FToxid-SLAGF with I; FToxid-SLAGG with C/N/CN;
FToxid-SLAGH with F/Cl; FToxid-SLAG? - all species (not recommended).
- called from 'Menu Window > Parameters'.
Beep when finished
- it is now possible to issue a sound ('friendly beep' unique to Equilib) when a calculation is finished.
This is useful in time consuming calculations when you want to know the moment the
results are ready.
- called from 'Menu Window > mouse-right-click on compound gas/aqueous/liquids/solids checkbox or solution + column'.
Like the Selection Window (see above), columns of the minimum and maximum values, etc. are now displayed.
Compounds and solutions that are selected for plotting are identified in the Post-Processor Species Selection Window.
FactSage 6.4 (2013)
When you first run Equilib then a summary of 'Current Databases Selected' and 'Current Data Search Options' is posted
and you are asked if you want to 'Load last system ?'.
If you reply 'Yes' then the last Equilib system is loaded as in previous versions.
If you reply 'No' you now have the the option to keep the current 'Databases Selected' and 'Data Search Options', or,
clear the 'Databases Selected', apply default settings to 'Data Search Options' and open the 'Data Search Window'."
There is a new default exclusion of species from compound species selection
When two or more databases are connected, the same species may appear in more than one database.
In such cases, a species should generally only be selected from one database.
Otherwise conflicts will probably occur.
In order to assist users in deciding which species to exclude, the FactSage developers have assigned priorities.
When you initially click on "pure solids", "pure liquids", or "gas" you may now see that several species marked with an "X" have not been selected.
That is, they have been excluded by default because of probable conflicts between databases.
The FactSage developers suggest that these species not be selected for this particular calculation.
If you wish to select species marked with an "X" you must first click on 'permit selection of "X" species'.
This will then override the default setting and permit you to select species as in FactSage 6.3.
This will also activate the 'suppress duplicates' button and enable you to define a database priority list as in FactSage 6.3.
IMPORTANT : For many calculations, it may frequently be advisable or necessary to de-select other species in addition to those marked with an "X."
This message will appear whenever you change the selected databases, or change the 'Data Search Options', or change
the components; that is any action that requires the databases to be re-scanned.
The purpose of the message is to simply advise you that the compound species selection may have changed.
The message will not appear when you load a new system or when you load a stored file.
Paraequilibrium refers to the concept that diffusion kinetics of interstitial solutes is much faster
than that of substitutional solutes.
For example in the Fe-Cr-C system carbon diffuses and equilibrates rapidly
whereas the diffusion of Fe and Cr between solid phases is slow and could be ignored.
A new paraequilibrium checkbox that performs paraequilibrium calculations
is now offered in the Equilibrium Menu Window.
In addition an Edit button opens an input box where the diffusing solutes (typically elemental carbon) are defined.
An example of parequilibrium calculations in the Fe-Cr-C system is presented later in the Phase Diagram section.
It is also possible to calculate the single phase with the minimum Gibbs energy for any given set of input conditions.
Such calculations may be of practical interest in physical vapour deposition where deposition from the vapour phase
is so rapid that phase separation cannot occur, resulting in a single-phase solid deposit.
Prior to 6.4 the maximum number of selected species and the maximum number of selected phases was 1500.
In FactSage 6.4 the maximum number of selected species is 3000.
Both total selected species and total selected phases are now posted in the Menu Window.
In the Results Window there are two types of displays - FACT Format and ChemSage Format.
You can display either or both Formats.
This is done by clicking on 'Output > Format > ...'.
The cut-off value is in the range 1e-75 to 0.01 and indicates the lower cut-off limit
for phase activities and solute concentrations.
It does affect the display of solution end-members.
In FactSage 6.4 there is new 'Show only stable phases' button.
When checked only the stable product phases are displayed.
Click on the 'Help' button for more information
The Scheil target calculation (option S) and the solidification calculations (option D that offered either Scheil or Equilibrium cooling) have been replaced by the one single option L - the cooLing calculation.
When option L is assigned to a solution phase you are presented with a new Cooling Calculation Window.
In the Cooling Calculation Window you can also display the transitions and summary pages in the Results Window
(this was not available for equilibrium cooling).
In 6.4 a new T-auto checkbox is now available.
By checking T-auto the starting temperature is now automatically calculated by the program
(internally Equilib performs a precipitate target calculation to identify when the
first phase is formed).
The actual starting value is rounded up to comply with the cooling step.
For example, if solidification first starts at 1580.23°C then a cooling step of 10°C (or 25°C)
would set the starting temperature at 1590°C (or 1600°C).
If the starting temperature cannot be calculated then the value defined in the
Final Conditions (1600°C) is used instead.
When the gas phase from more than one database is selected there may be duplicate entries for gas species.
In such a case the calculated equilibrium will be incorrect.
In FactSage 6.4 a warning message is now issued when duplicates gas species are detected
and the offending species are flagged with '_d'.
Duplicates can be avoided by checking the 'suppress duplicates' checkbox in the Menu Window .
Traditionally the maximum length of a line in the Results Window has been limited to 80 characters.
In FactSage 6.4 this restriction is no longer applied and some of the results, particularly the display in the ChemSage Format,
have much longer lines.
Both font size and Window display size are retained next time Equilib is run.
To return to the original settings go to the Edit toolbox menu and click on 'Default font wnd Window size'.
FactSage 7.0 (2015)
Click on the units menu to enter the Units Window
you can select either 'Metric SI units' or 'English units'. For example:
In FactSage 7.0 it is now possible to mix the units and select various combination, for example :
FactSage 7.1 (2017)
The option 'include molar volume data and physical properties data' takes into account the effect of thermal expansivity
and compressibility data on the molar volume of the species and effects the 'VdP' term used in the calculation.
In addition physical properties such as bulk modulus, Curie temperature, electrical conductivity, thermal conductivity ,
thermal expansivity, viscosity etc. are displayed when available.
The maximum number of selected product solutions is now 150 (was 40 in FactSage 7.0). The maximum number of product species (3000) and product phases (1500) remain unchanged.
FactSage 7.2 (2018)
Equilib and Phase Diagram engage the ChemApp Gibbs energy minimizer which is programmed in FORTRAN.
In FactSage 7.2 we have changed the FORTRAN complier.
We now employ the Intel Compiler which produces optimized code that is more compact and runs significantly faster.
In addition the superior error checking features of the new compiler enable us to produce a code
that is less likely to contain bugs.
In the Equilib Reactants Window you specify a set of reactant
amounts, for example:
50 mol SiO2 + 30 mol CaO + 20 mol MgO
But you may open a Reaction Table and specify multiple sets of reactant amounts.
With the Reaction Table you specify various sets of
reactant amounts as well as their product temperatures and
pressures - each set resulting in a separate equilibrium calculation.
Here the Reaction Table shows the entry 5 separate equilibrium calculations (rows 1 - 5).
As new amounts are entered the totals are updated.
For example, with the entry of 40 mole MgO on row 5 the display updates the total:
After closing the Reaction Table you open the Menu Window and select the Table option.
This causes the original amounts and Final Conditions to be replaced by <table> .
The product equilibrium is calculated in the usual manner (click on Calculate >>)
and 5 pages of output are displayed in the Results Window
1 - The Table option is selected in the Menu Window
In general the Reaction Table is used to specify sets of input amounts with
their product temperature and pressure.
In FactSage 7.2 it may be possible to change the type of calculation,
for example ignore the product temperature,
but still employ the Reaction Table to define the input amounts.
For example, in the above case the initial temperature of precipitation of solids
from the slag phase could be calculated
by specifying FToxid-Slag as a precipitate target phase (option 'P')
and not specifying the final temperature ('blank').
This causes a conflict with the Reaction Table where the final temperature is defined.
The Warning - Conflict with Reaction Table is posted in the Menu Window
as shown in the following screenshot.
But in FactSage 7.2 the calculation is now permitted
and the temperature specified in the Reaction Table is ignored.
1 - In the Menu Window option 'P' is applied to FToxid-Slag and the final temperature is undefined ('blank')
These values will appear at the top of the page in the Equilib Results Window.
In the case of a range of values with multiple output pages
(e.g. T = 1000, 1100, 1200, ...)
the elapsed time for the first page (T = 1000) will tend to be slightly longer than the others
since it also includes the time to load the data from the databases.
- see Slide Show 'Equilib - Regular Features - Section 19'
- refreshing compound default selection -
- see Slide Show 'Equilib - Advanced Features - Section 14'
The Print cut-off is set in the Parameters Window and limits the length of output in the Results Window.
It only affects the display; it has no effect upon the calculation.
To display the solution extended menu point to the '+' column of the solution (Equilib Menu Window) and then click on the mouse-right-button.
Solution extended menu - FactSage 6.3
Solution extended menu - FactSage 6.4
Option L can be assigned to any solution phase (including the gas phase).
However cooling is most meaningful when the initial solution is a liquid
since the cooling calculations relate to solidification.
Prior to 6.4 for solidification calculations it was necessary to provide an initial starting temperature
(for example 1600°C) in the temperature Final Conditions input box.
For meaningful solidification calculations this would be a value where the solution phase
(for example SLAG) is 100% liquid.
If the cooling phase is the gas phase then the precipitates could be any or all of the other
compound and solution phases.
To activate the gas phase, first select the gas species in the usual way.
Then with the mouse-right-button click on the gas '+' checkbox in the compound species frame of the Menu Window
- this will open the Species Selection window.
Point to the '+' column of any selected gas species and then click with the mouse-right-button and
assign option L.
To accommodate the expanded output the size of the window display can be increased by pointing to the borders
and stretching the edges of the Window.
In addition the font size of the display can be changed by clicking on the screen.
Enter Ctrl+ to increase font size, Ctrl- to decrease the font size
and Ctrl 0 to return to the default setting.
SI units: T(K), P(bar), Energy(J), Mass(mol), Volume(litre)
English Units: T(F), P(psi), Energy(BTU), Mass(lb), Volume(Ft3)
T(F), P(psi), Energy(kwh), Mass(lb), Volume(Ft3)
T(C), P(psi), Energy(kwh), Mass(lb), Volume(Ft3)
T(C), P(psi), Energy(kwh), Mass(mol), Volume(Ft3)
T(K), P(Pa), Energy(J), Mass(lb), Volume(litre)
.
Row 5: the total reactants = 100 (mole)
2 - Results Window showing the equilibrium calculation for the first set of reactants
- row 1 in the Reaction Table.
2 - In the Results Window the precipitate temperature for page 1 is 1382.45 C
.
In the Equilib Parameters Window the show options in the Output Frame have been enhanced.
After the equilibrium has been calculated, you can now display
the date and elapsed time (if more than 0.1 sec) for the calculation.