Temperature dependent interface mobility

[VenkatesanJv]

Dear Sir,

For Simulating Austenite to pearlite transformation , Initially we used constant values as an input for interface mobility in phase interaction data. Now i would like to give input values as temperature dependent.

In the Micress_53_manual it is given that, for this case a text file describing this dependency has to be specified and it should consist of two columns: the first being the temperature and the second the value of the corresponding mobility or surface energy at this temperature. Please note that the check for the compliance of the mobility, surface energy and constant time-step with the stability criteria has been disabled in this case

a) In the above paragraph am not understanding the last line , please explain this
b) how we have to write temperature dependent interface mobility values in the micress code.
c) if we have to provide the values in text file, then tell how the values are arranged in the text file.

Please provide example for both (b) and (c) questions. Please help me

Thanks in advance

[Bernd]

Dear VenkatesanJv,

Why are you using the manual of the quite old MICRESS version 5.3? Aren't you working with a recent MICRESS version? You should rather refer to the manual of version 6.1 which is available on this web site (under "Downloads")!

Let me answer your questions, independent from the exact MICRESS version:

a) The somewhat cryptical sentence in the old MICRESS manual means that in case you are using constant time steps (you are strongly recommended to use automatic time stepping instead!), the simulation may be numerically unstable, depending on the combination of choices for the time step width, the interface mobility, and the interface energy. A compliance check is done only at program start, but is omitted in case of temperature-dependent mobility, because mobility values are expected to change during simulation in this case!
This fact has no meaning if you are using automatic time stepping! Then, time steps are always chosen such as to comply to the other two parameters. This is also the case with temperature-dependent mobilities!

b) We won't allow you to write anything into the MICRESS code , but you should use the keyword "temp_dependent" instead of "constant" in section "Phase interaction data" of the driving file, followed by the name of the input file in the following line.

c) The file should be of ASCII format and contain at least two columns. By default, the first is the temperature in Kelvin, the second is the corresponding interface mobility value. Alternatively, you can specify the corresponding columns in the way:

<filename> columns x y

An example for the use of temperature-dependent mobility can be found in the "Examples" directory of your standard installation ("Grain_Growth_Profiles_dri).

Best wishes

Bernd

[VenkatesanJv]

Dear Brend

Thank you for your kind reply..


Regards
Venkatesan J

[deepumaj1]

Dear Bernd,
I want to give the temperature dependent mobility using the following equation(please find attached). I have also read literatures on micress which have implemented this equation. Which option in micress should I use to implement this? Where can I input the values for the activation energy, etc?

[Bernd]

Dear deepumaj1,

Until now we did not implement an input of the interface mobility µ in format of an exponential equation (like e.g. for diffusivities). Therefore the only way to do it is to tabulate the function in the required temperature range and put it into an ASCII file (first column: T, second column µ in cm⁴/(Js)). Then you can use "temperature_dependent" as explained before.

Bernd