calculation of temperature/composition sections through multicomponents
application is used for calculating temperature / composition vertical
sections through multicomponent phase diagrams for a fixed pressure
but with varying temperatures and (constrained) compositions.
Graphical output is produced as the calculations proceed showing the
phase boundaries calculated by MTDATA.
Two different algorithms for calculating isopleths are available within
MTDATA. In the first algorithm (ISOPLETH),
the graph displayed consists of a series of discrete points ie not
joined up. Options are available to perform more calculations within a
given area and to label individual phase fields. Following
the calculations the graph may be plotted with all the calculated
points joined up.
the second algorithm (NEW_ISOPLETH), the calculation follows each line
corresponding to a particular phase boundary across the phase
diagram using the concept of zero phase fraction. Again options are
available to label individual phase fields. For
each algorithm the macro provides prompts to help the user to decide
what to type in next.
asking for the isopleth to be calculated it is necessary to define a
datafile, to classify any phases required to be absent or identified as
giving rise to miscibility gaps, to specify the range of temperatures
considered and the temperature tolerance (typically 0.1). Also the
of compositions must be defined by setting start and final composition
groups and specifying the number of compositions to be examined between
them. All this can be set up using the normal APPLICATION commands
other parameters need to be defined, the composition tolerance
(typically 0.0001), the number of temperature intervals (perhaps 30).
will be prompted for.
options are available ie to plot liquidus or solidus curves or to
ignore designated phases, these are invoked by setting the user
variable Defn_Method to 2 (the default
value is 0).
USER_VARIABLE(Defn_Method) = 2 !
user variables, Liq_Solidus, liq_phs_nos and ign_phs_nos provide the
user variable Liq_Solidus allows a resticted set of the available lines
to be calculated and plotted, liq_phs_nos allow a particular phase (or
phases) to be assigned as the liquid phase and ign_phs_nos allows
certain phases to ignored in terms of the definition of the phase
boundaries although still present in the calculations.
the liquidus curve is calculated defined as the highest temperature at
which a solid is still present or at which a liquid miscibility gap is
1 just the liquidus curve is required
defined as the highest temperature at which a solid is still present
2 just the solidus curve is required
defined as the highest temperature at which no liquid is present.
3 all boundaries are required except those
corresponding to those phases that are to be ignored, defined by the
user variable ign_phs_nos
user variables liq_phs_nos and ign_phs_nos should be entered within
quotes. If a list of numbers is
given they be separated by + signs. Multiple numbers for liq_phs_nos
both liquid and gas phases to be assigned as high temperature phases eg