START_WIZARD

This command is for the SCHEIL module.

About the Scheil-Gulliver Solidification Simulations

Use this command to use the START_WIZARD with step-by-step prompts to create a Scheil simulation.

You are prompted for settings including the major element or alloy, composition input in mass (weight) percent, the alloying elements, the temperature, fast diffusing components, and whether any phase should have a miscibility gap check. There are additional prompts included in the Start Wizard if Use back diffusion or SOLUTE TRAPPING commands are set to Yes to enable back diffusion and solute trapping, respectively.

The Scheil with back diffusion feature is only available for systems with diffusion data, i.e. this model requires the use of a mobility database.

Use the other commands to make changes to settings that are not included in this wizard.

EVALUATE_SEGREGATION_PROFILE
GLOBAL_MINIMIZATION
LIQUID_PHASE_NAME
SAVE_FILE_NAME
STORED_COMPOSITION_TYPE
TEMPERATURE_STEP
TERMINATION_CRITERIA

If you also have a license for the Diffusion Module (DICTRA), you can import a previously calculated Scheil segregation profile into the software using the command INPUT_SCHEIL_PROFILE.

Syntax	START_WIZARD
Prompt	The following is a list of the prompts. Press <Enter> to accept the defaults that are shown between the forward slashes (/default/). Database /<Default>/: The available thermodynamic database and its version are available to enter (based on license). Enter `?` for a list. Major element or alloy: The major element in the system, e.g. Fe for a steel. Composition input in mass (weight) percent? /Y/: Set whether to specify the `Composition input in mass (weight) percent` (the default) or in `Mole percent`. Enter `Y` for mass percent and `N` for mole percent. 1st alloying element: You can specify all the alloying elements and their corresponding compositions on the same line when you are prompted to specify your first alloying element. For example, you can enter `Cr 5 Ni 1 Mo 0.5 C 0.01 N 0.02`. You can directly specify mass or mole percent after the name (for example, enter `Cr 5`). If this is not specified, then you are prompted to enter it separately. Mass (weight) percent /1/ 2nd alloying element: Specify the other alloying elements in the same way as you specify the first (for example, `c 1`). Mass (weight) percent /1/ Next alloying element: After you have specified your last alloying element, press <Enter> when requested to specify the next element. This ends the process of defining the bulk composition of the alloy system. Temperature (C) /2000/: Enter a value for the temperature in degrees C (Celsius) . This value should be sufficiently high so that the solidification simulation starts with the alloy system in the liquid single-phase region. Decide which phases (if any) to reject at the `Reject phase(s)` prompt. Enter the name of the phases to reject or press <Enter> for `NONE`. Decide whether to `Restore phase(s)`. You may want to restore a phase that you rejected when you ran the simulation earlier, or you may want to restore a phase that is rejected by default in your database. Enter the name of the phases to restore or press <Enter> for `NONE`. Then you are asked to confirm whether these phases should be retained in this system: OK? /Y/: Press <Enter> to accept the default `Y` or type `N` and press <Enter>. Thermodynamic data about the alloy system you defined is retrieved from the database. Should any phase have a miscibility gap check? /N/: If you answer `Y`, you are prompted to specify the `Phase with miscibility gap`. Answer with a solution phase name(s) (e.g. `FCC`) as well as the `Major constituents for sublattice` (for each sublattice site) (for this example, `Cr` is entered for sublattice 1 and `C` for sublattice 2). Press Enter to specify another phase. Fast diffusing components: /None/: Enter the elements that diffuse fast in solid phases and can assume to be in equilibrium in the whole phase. E.g. C in a steel.

Syntax

START_WIZARD

Prompt

The following is a list of the prompts. Press <Enter> to accept the defaults that are shown between the forward slashes (/default/).

Database /<Default>/:

The available thermodynamic database and its version are available to enter (based on license). Enter ? for a list.

Major element or alloy:

The major element in the system, e.g. Fe for a steel.

Composition input in mass (weight) percent? /Y/:

Set whether to specify the Composition input in mass (weight) percent (the default) or in Mole percent. Enter Y for mass percent and N for mole percent.

1st alloying element:

You can specify all the alloying elements and their corresponding compositions on the same line when you are prompted to specify your first alloying element. For example, you can enter Cr 5 Ni 1 Mo 0.5 C 0.01 N 0.02.

You can directly specify mass or mole percent after the name (for example, enter Cr 5). If this is not specified, then you are prompted to enter it separately.

Mass (weight) percent /1/

2nd alloying element:

Specify the other alloying elements in the same way as you specify the first (for example, c 1).

Mass (weight) percent /1/

Next alloying element:

After you have specified your last alloying element, press <Enter> when requested to specify the next element. This ends the process of defining the bulk composition of the alloy system.

Temperature (C) /2000/:

Enter a value for the temperature in degrees C (Celsius) . This value should be sufficiently high so that the solidification simulation starts with the alloy system in the liquid single-phase region.

Decide which phases (if any) to reject at the Reject phase(s) prompt. Enter the name of the phases to reject or press <Enter> for NONE.

Decide whether to Restore phase(s). You may want to restore a phase that you rejected when you ran the simulation earlier, or you may want to restore a phase that is rejected by default in your database. Enter the name of the phases to restore or press <Enter> for NONE.

Then you are asked to confirm whether these phases should be retained in this system:

OK? /Y/:

Press <Enter> to accept the default Y or type N and press <Enter>. Thermodynamic data about the alloy system you defined is retrieved from the database.

Should any phase have a miscibility gap check? /N/:

If you answer Y, you are prompted to specify the Phase with miscibility gap. Answer with a solution phase name(s) (e.g. FCC) as well as the Major constituents for sublattice (for each sublattice site) (for this example, Cr is entered for sublattice 1 and C for sublattice 2).

Press Enter to specify another phase.

Fast diffusing components: /None/:

Enter the elements that diffuse fast in solid phases and can assume to be in equilibrium in the whole phase. E.g. C in a steel.

Back Diffusion and Solute Trapping Settings

The following prompts are included with the Start Wizard at various points in the set up if the:

USE_BACK_DIFFUSION command is set to Y to enable back diffusion
SOLUTE_TRAPPING command is set to Y to enable solute trapping

Syntax	START_WIZARD
Back Diffusion settings	Mobility Database /<Default>/: The available mobility database and its version are available to enter (based on license). Enter `?` for a list. You then are shown a list of what phases are available for the database and the defined system and have the opportunity to reject or restore phases at the next prompts. Reject phase(s) /NONE/: Restore phase(s): /NONE/: Then you are asked to confirm whether these phases should be retained in this system: OK? /Y/: Press <Enter> to accept the default `Y` or type `N` and press <Enter>. Temperature time dependence /LINEAR/: Specify the type of temperature time dependence. Press <Enter> to accept this default. An increased value moves the result from equilibrium toward a Scheil-Gulliver calculation. LINEAR is the only option and it corresponds to a constant cooling rate. Cooling rate (K/s) /.1/: Specify the cooling rate in Kelvin per second (K/s). An increased value moves the result from equilibrium toward a Scheil-Gulliver calculation. Expression for secondary dendrite arm spacing /CONSTANT/: Secondary dendrite arm spacing is the distance in meters (m) between two secondary dendrite arms. Specify the type of secondary dendrite arm spacing by entering `CONSTANT` (the default) or `POWER_LAW`. An increased value moves the result from equilibrium toward a Scheil-Gulliver calculation. Use `CONSTANT` for a constant dendrite arm spacing. If you choose this, then enter a value for the `Secondary dendrite arm spacing (m) /5E-05/:` prompt. `POWER_LAW` in the form `c*(cooling rate)^-n` where `c` and `n` are entered in the next prompts. If you choose this, then enter a value for the `Exponent n /.33/:` and `Scaling factor c /5E-05/:` Primary phase /AUTOMATIC/: The primary phase is the phase where the back diffusion takes place. If `Automatic` is selected (or kept as the default), the program tries to find the phase which gives the most back diffusion. To override this setting, choose a specific primary phase from the list. For back diffusion, only phases with diffusion data can be used as primary phases.
Solute Trapping settings	Expression for solidification speed /SCANNING_SPEED_AND_ANGLE/: SCANNING_SPEED_AND_ANGLE is currently the only available option. It is calculated as scanning speed * cos(alpha) where scanning speed and the angle alpha are given by the user. Decreasing the value moves the result toward a Scheil-Gulliver calculation. Scanning speed (m/s) /1/: Enter the Scanning speed to calculate the solidification speed, Vs = V_scanning * cos(α) m/s, where V_scanning is the user specified scanning speed. Alpha (degrees) /45/: Enter an Alpha value in degrees, which is the alpha angle, α, between the solid/liquid boundary and scanning direction. Primary phase /AUTOMATIC/: If `Automatic` is selected (or kept as the default), the program tries to find the phase which gives the most solute trapping. To override this setting, choose a specific primary phase from the list. For solute trapping, only phases that dissolve all elements in the system can be used as primary phases.

Syntax

START_WIZARD

Back Diffusion settings

Mobility Database /<Default>/:

The available mobility database and its version are available to enter (based on license). Enter ? for a list.

You then are shown a list of what phases are available for the database and the defined system and have the opportunity to reject or restore phases at the next prompts.

Reject phase(s) /NONE/:

Restore phase(s): /NONE/:

Then you are asked to confirm whether these phases should be retained in this system:

OK? /Y/:

Press <Enter> to accept the default Y or type N and press <Enter>.

Temperature time dependence /LINEAR/:

Specify the type of temperature time dependence. Press <Enter> to accept this default.

An increased value moves the result from equilibrium toward a Scheil-Gulliver calculation.

LINEAR is the only option and it corresponds to a constant cooling rate.

Cooling rate (K/s) /.1/:

Specify the cooling rate in Kelvin per second (K/s). An increased value moves the result from equilibrium toward a Scheil-Gulliver calculation.

Expression for secondary dendrite arm spacing /CONSTANT/:

Secondary dendrite arm spacing is the distance in meters (m) between two secondary dendrite arms. Specify the type of secondary dendrite arm spacing by entering CONSTANT (the default) or POWER_LAW.

An increased value moves the result from equilibrium toward a Scheil-Gulliver calculation. Use

CONSTANT for a constant dendrite arm spacing. If you choose this, then enter a value for the Secondary dendrite arm spacing (m) /5E-05/: prompt.
POWER_LAW in the form c*(cooling rate)^-n where c and n are entered in the next prompts. If you choose this, then enter a value for the Exponent n /.33/: and Scaling factor c /5E-05/:

Primary phase /AUTOMATIC/:

The primary phase is the phase where the back diffusion takes place.

If Automatic is selected (or kept as the default), the program tries to find the phase which gives the most back diffusion. To override this setting, choose a specific primary phase from the list. For back diffusion, only phases with diffusion data can be used as primary phases.

Solute Trapping settings

Expression for solidification speed /SCANNING_SPEED_AND_ANGLE/:

SCANNING_SPEED_AND_ANGLE is currently the only available option. It is calculated as scanning speed * cos(alpha) where scanning speed and the angle alpha are given by the user.

Decreasing the value moves the result toward a Scheil-Gulliver calculation.

Scanning speed (m/s) /1/:

Enter the Scanning speed to calculate the solidification speed, Vs = V_scanning * cos(α) m/s, where V_scanning is the user specified scanning speed.

Alpha (degrees) /45/:

Enter an Alpha value in degrees, which is the alpha angle, α, between the solid/liquid boundary and scanning direction.

Primary phase /AUTOMATIC/:

If Automatic is selected (or kept as the default), the program tries to find the phase which gives the most solute trapping. To override this setting, choose a specific primary phase from the list. For solute trapping, only phases that dissolve all elements in the system can be used as primary phases.