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| tutorials:t3 [2019/07/30 15:15] – [T3: Stepped equilibrium calculations] pwarczok | tutorials:t3 [2023/08/01 12:39] (current) – [T3: Stepped equilibrium calculations] pwarczok |
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| //This tutorial was tested on \\ | //This tutorial was tested on \\ |
| MatCalc version 6.02 rel 1.003 \\ | MatCalc version 6.04 rel 1.001 \\ |
| license: free \\ | license: free \\ |
| database: mc_fe.tdb // | database: mc_fe.tdb // |
| Re-open the file saved from [[tutorials:T2 |Tutorial 2]] and load the calculation state **'Equil @ 600°C'**. | Re-open the file saved from [[tutorials:T2 |Tutorial 2]] and load the calculation state **'Equil @ 600°C'**. |
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| | {{:tutorials:t3:img:t3_file_open_6050006.png| Open MatCalc workspace }} |
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| | {{:tutorials:t3:img:t3_load_calc_state_6050006.png| Load calc state }} |
| ===== Stepped equilibrium calculation with varying temperature ===== | ===== Stepped equilibrium calculation with varying temperature ===== |
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| ==== Running the stepped calculation ==== | ==== Running the stepped calculation ==== |
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| In phase status window, remove graphite phase. Select **'Stepped calculation...'** from the **'Calc'** menu or click on the {{:tutorials:t3:img:icon_calc_stepped.png| MatCalc stepped calculation}} icon. The **'Step equilibrium'** window will appear. Select **'Temperature'** (the uppermost choice in the left-hand column). \\ | In phase status window, remove graphite phase. |
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| | {{:tutorials:t3:img:t3_remove_graphite_6050006.png| Remove graphite phase }} |
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| | Select **'Stepped calculation...'** from the **'Calc'** menu or click on the {{:tutorials:t3:img:icon_calc_stepped.png| MatCalc stepped calculation}} icon. |
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| | {{:tutorials:t3:img:t3_global_stepped_calculation_6050006.png| Open stepped calculation window }} |
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| | The **'Step equilibrium'** window will appear. Select **'Temperature'** (the uppermost choice in the left-hand column). \\ |
| In the **'Range'** box, the default **'Start'**, **'Stop'** and **'Step interval'** values are 400, 1600 and 25 respectively. Keep these values and verify that the **'Temperatures in Celsius'** option has been selected. The step direction is unimportant, and it is not necessary to enter the interval as **'-25'** if stepping in a negative direction. The contents of the **'Vary'** and **'Boundary conditions'** boxes are currently greyed-out because they are not applicable to a temperature-step calculation. Click on the **'Go'** button at the bottom right of the window. | In the **'Range'** box, the default **'Start'**, **'Stop'** and **'Step interval'** values are 400, 1600 and 25 respectively. Keep these values and verify that the **'Temperatures in Celsius'** option has been selected. The step direction is unimportant, and it is not necessary to enter the interval as **'-25'** if stepping in a negative direction. The contents of the **'Vary'** and **'Boundary conditions'** boxes are currently greyed-out because they are not applicable to a temperature-step calculation. Click on the **'Go'** button at the bottom right of the window. |
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| {{:tutorials:t3:img:t3_step_equilibrium_2016.png| MatCalc step equilibrium}} | {{:tutorials:t3:img:t3_step_equilibrium_6050006.png| MatCalc step equilibrium}} |
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| ==== Output ==== | ==== Output ==== |
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| All the equilibria listed above are stored in a buffer. In other words, a buffer is a collection of calculation states, with each calculation state created at a different temperature. The default buffer is named **'_default_'**, and its contents are overwritten when a new stepped calculation is carried out. \\ | All the equilibria listed above are stored in a buffer. In other words, a buffer is a collection of calculation states, with each calculation state created at a different temperature. The default buffer is named **'_default_'**, and its contents are overwritten when a new stepped calculation is carried out. \\ |
| To be able to keep more than one set of stepped equilibria, additional buffers must be created. Firstly, rename the existing default buffer using **'Global > Buffers > Rename'**. Type **'T=400 to 1600°C'** into the **'New buffer name'** box and click **'OK'**. Then, create a new buffer using **'Global > Buffers > Create'**. This new buffer will contain the results from a new stepped equilibrium calculation in which the carbon content is varied from 0 to 1.5 wt.% at 500°C, so enter the name **'C=0 to 1.5 at 500°C'**. Note that buffers can be selected from the drop-box in the toolbar area or using 'Global > Buffers > Select'. | To be able to keep more than one set of stepped equilibria, additional buffers must be created. Firstly, rename the existing default buffer using **'Global > Buffers > Rename'**. Type **'T=400 to 1600°C'** into the **'New buffer name'** box and click **'OK'**. |
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| | {{:tutorials:t3:img:t3_global_rename_buffer_6050006.png| Open rename buffer window}} |
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| | {{:tutorials:t3:img:t3_rename_buffer_6050006.png| Rename buffer window}} |
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| | Then, create a new buffer using **'Global > Buffers > Create'**. |
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| | {{:tutorials:t3:img:t3_global_create_buffer_6050006.png| Open create buffer window}} |
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| | This new buffer will contain the results from a new stepped equilibrium calculation in which the carbon content is varied from 0 to 1.5 wt.% at 500°C, so enter the name **'C=0 to 1.5 at 500°C'**. |
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| | {{:tutorials:t3:img:t3_create_buffer_name_6050006.png| Create buffer window}} |
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| | Note that buffers can be selected from the drop-box in the toolbar area or using 'Global > Buffers > Select'. |
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| {{:tutorials:t3:img:t3_buffer_toolbox_2016.png| MatCalc buffer toolbox}} | {{:tutorials:t3:img:t3_buffer_toolbox_2016.png| MatCalc buffer toolbox}} |
| In the **'Boundary conditions'** box, ensure that the element selected is **'C'**, and enter the temperature as **'500'**. Ensure that in the **'vary'** box, **'global comp'** is selected, and that in the **'Options'** column, **'Temperatures in Celsius'** and **'Composition in weight percent'** are both selected, then click on **'Go'**. | In the **'Boundary conditions'** box, ensure that the element selected is **'C'**, and enter the temperature as **'500'**. Ensure that in the **'vary'** box, **'global comp'** is selected, and that in the **'Options'** column, **'Temperatures in Celsius'** and **'Composition in weight percent'** are both selected, then click on **'Go'**. |
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| {{:tutorials:t3:img:t3_step_equilibrium_element_2016.png| MatCalc step equilibrium}} | {{:tutorials:t3:img:t3_step_equilibrium_element_6050006.png| MatCalc step equilibrium}} |
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| The contents of the **'console'** window should appear as follows: | The contents of the **'console'** window should appear as follows: |
| Similarly to the temperature-step calculation, the output consists of a series of equilibria evaluated at the specified step-values. The first of these corresponds to the carbon content of 0.4 wt.% entered in the **'System composition'** box in [[tutorials:T2 | Tutorial 2]]. The carbon content is then increased in 0.05 wt.% steps up to the maximum value of 1.5 wt.%. The 'Changing step direction' line marks the beginning of the second set of equilibria, in which the carbon content is decreased. | Similarly to the temperature-step calculation, the output consists of a series of equilibria evaluated at the specified step-values. The first of these corresponds to the carbon content of 0.4 wt.% entered in the **'System composition'** box in [[tutorials:T2 | Tutorial 2]]. The carbon content is then increased in 0.05 wt.% steps up to the maximum value of 1.5 wt.%. The 'Changing step direction' line marks the beginning of the second set of equilibria, in which the carbon content is decreased. |
| At 500°C, the stable phases are BCC_A2 and CEMENTITE across almost the whole composition range, but between the final two equilibria there is a line beginning with **'Xsol'**. The line below this gives the carbon content at which cementite becomes unstable, both in mole fraction **'X(C)'** and in weight percent **'WP(C)'**.\\ | At 500°C, the stable phases are BCC_A2 and CEMENTITE across almost the whole composition range, but between the final two equilibria there is a line beginning with **'Xsol'**. The line below this gives the carbon content at which cementite becomes unstable, both in mole fraction **'X(C)'** and in weight percent **'WP(C)'**.\\ |
| Create a third buffer named **'C=0 to 1.5 at 800°C'** and perform a stepped calculation with the same composition range but at a temperature of 800°C. The output in this case includes three **'Xsol'** lines, corresponding to changes in phase stability: | Create a third buffer named **'C=0 to 1.5 at 800°C'** and perform a stepped calculation with the same composition range but at a temperature of 800°C. |
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| | {{:tutorials:t3:img:t3_create_third_buffer_name_6050006.png| Create buffer window}} |
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| | {{:tutorials:t3:img:t3_step_equilibrium_element_800_6050006.png| MatCalc step equilibrium}} |
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| | The output in this case includes three **'Xsol'** lines, corresponding to changes in phase stability: |
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| <code> | <code> |
| The **'console'** window provides information on which phases are stable at a given temperature and carbon content, but not on the phase fractions or compositions. However, this detailed information is stored in the buffers and can be found by selecting **'Global > Buffers > Edit buffer states'**. | The **'console'** window provides information on which phases are stable at a given temperature and carbon content, but not on the phase fractions or compositions. However, this detailed information is stored in the buffers and can be found by selecting **'Global > Buffers > Edit buffer states'**. |
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| {{:tutorials:t3:img:t3_edit_and_load_buffer_states_6001000.png| MatCalc edit and load the buffer states}} | {{:tutorials:t3:img:t3_global_edit_buffer_states_6050006.png| Open edit and load buffer states window}} |
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| | A new window appears with the list of the calc states stored in the buffer. The upper part of the **'step value...'** area contains a drop-box for selecting a buffer, and the lower part gives a list of the step-values at which equilibria have been evaluated. These are either temperature or carbon content values, depending on the buffer chosen, and their units are those specified in the **'Step equilibrium'** window when setting up the calculation. The **'Tsol'** or **'Xsol'** values are also stored. If the **'auto load'** box at the bottom left is ticked, clicking on a step-value loads the equilibrium, and the contents of the **'Phase summary'** and **'Phase details'** are immediately updated with phase fraction and composition details for this equilibrium. |
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| | {{:tutorials:t3:img:t3_edit_and_load_buffer_states_6001000.png| MatCalc edit and load buffer states}} |
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| The upper part of the **'step value...'** area contains a drop-box for selecting a buffer, and the lower part gives a list of the step-values at which equilibria have been evaluated. These are either temperature or carbon content values, depending on the buffer chosen, and their units are those specified in the **'Step equilibrium'** window when setting up the calculation. The **'Tsol'** or **'Xsol'** values are also stored. If the **'auto load'** box at the bottom left is ticked, clicking on a step-value loads the equilibrium, and the contents of the **'Phase summary'** and **'Phase details'** are immediately updated with phase fraction and composition details for this equilibrium. | |
| The next two tutorials demonstrate how to produce graphical plots of phase fractions, compositions and many other quantities as a function of the stepped variable. | The next two tutorials demonstrate how to produce graphical plots of phase fractions, compositions and many other quantities as a function of the stepped variable. |
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