MICRESS 6.0 released

new developments, future functionalities, hints for further applications of MICRESS
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MICRESS 6.0 released

Post by admin » Fri Oct 21, 2011 12:30 pm

MICRESS® Version 6.0 has been released in October 2011.It comprises a number of improvements and new functionalities. Of course we also attempted to fix all bugs reported by the user community.

Version 6.0 comes as a 64 bit version and draws back on the most recent version of Thermo-Calc TQ-interface TQ-7. To profit from the 64 bit version our customers have to update their Thermo-Calc installation to the most recent version of Thermo-Calc Classic TCC-S (including all its updates until September 2010). The update to the latest TCC version becomes necessary, as the format of the .ges5 files has changed with the newest version S and the 64 bit version needs compatible 64 bit coded ges5 files.

For those customers intending to stay with their present .ges files (corresponding to Thermo-Calc Classic TCC-R) we included also executables staying with the old standard as a 32 bit executable as before. In total the following executables being provided for MICRESS 6.0 for both Linux and Windows:

MICRESS64_TQS (the new standard)
MICRESS32_TQS
MICRESS32_TQR
MICRESS32_noTQ (no coupling to databases)
MICRESS64_noTQ (no coupling to databases)

Please note that some of the new features are not available in the “R”-type version. All future developments will be based on the MICRESS64_TQS. The “R”-type versions will not be further supported in future releases.

Input/Output

  • a time interval for updating enthalpy data from TQ now can be specified when using release of latent heat. This can improve performance considerably.

    a specific interval for each individual phase interaction can be specified in addition to the time interval for complete relinearisation. This provides more flexibility for performance optimization.

    an arbitrary prefactor can be specified for the diffusion time stepping of each diffusion term (line of the diffusion matrix).

    new option to read initial 1D-temperature distributions from file in case of temperature coupled simulations

    new and improved averaged output of the interface velocity (outVel)

    A user-defined hysteresis factor for phMin can now be specified to cope with fluctuation problems which deteriorate performance
output intervals for tabulated data ( .Tabx files)

output intervals for tabulated data can now be selected independently from the output intervals for the field values.

orientation selection „randomZ“

“randomZ” is included as additional option for specification of orientations and represents the projection of the misorientation with respect to the z direction into 2D. It is very useful e.g. for the simulation of grain selection in a temperature gradient in 2D.

DSC-mode output

This option allows the output of enthalpy data (and thus plotting of a virtual DSC curve) for simulations where a constant cooling/heating is applied.


improved performance

Finite difference correction „FD-correction“

The numerical solution of the phase-field equation based on the finite-differences method naturally implies a discretization error. The accuracy of the numerical phase-field solution generally scales with number of numerical cells used to resolve the finite-sized interface
regions. However, for sake of numerical efficiency, MICRESS simulations are typically run with approximately 4 interface cells only. In some simulations, especially in cases of inter-face-controlled growth, significant deviations from the analytical sharp-interface solution were observed.

In the new release, this problem has been overcome by an improved numerical discretization, optimized for the special interface profile used in the MICRESS model. The consideration of the sinusoidal profile function enables an almost exact quantification of the bias evoked by grid spacing and interface width, which then can be compensated a priori. The new finite-differences correction allows obtaining highly accurate results with 3 or 4 interface cells only. A detailed description of the new implemented model is published in [Eiken 2011, MRS Spring meeting].

To activate the new option add the key-word 'fd_correction' to the choice of the phase-field potential. For interface-controlled processes set the number of interface cells to 4. When adjusting a former simulation, note that a reduced number of interface cells usually allows for a larger grid spacing, which may significantly reduce computation time. In concentration-coupled processes small interface widths are beneficial to reduce artificial trapping phenomena. For direct adjustment of a former simulation, the interface width should be reduced by at least one cell.


consideration of anti-trapping currents

Schemes to correct for artefacts evoked by the diffuse interface (“anti-trapping currents”) have been implemented and validated for several examples

TQ coupling

Further optimisation providing more stability, especially with respect to the use of composition sets



New functionalities


effective phases

A new approach is included which allows treating eutectic or other fine-structured phase mixtures in a thermodynamically consistent way as an effective phase. The fine two-phase regions (e.g. pearlite) which cannot be resolved in a phase-field simulation are replaced by a diffuse phase mixture.

paraequilibrium / NPLE and related models

The paraequilibrium and NPLE models in MICRESS have been further improved and completed, so that the user now can draw on four options for advanced redistribution control independently for each alloying element:

normal: standard redistribution behavior
nple: redistribution-based nple model
para: redistribution-based paraequilibrium model (also for use with linearized phase diagram descriptions)
paraTQ: thermodynamically-based paraequilibrium model which uses the Thermo-Calc paraequilibrium model (only available with TQS)


Contact angles and kinetics of phase and grain junctions

Already in the previous release, the option 'multi-obstacle' was introduced for the choice of the phase-field potential. In contrast to 'double-obstacle', this option allows for an accurate reproduction of contact angles in junctions where interfaces with different interface energies adjoin. In the new release, the underlying model has been further improved with respect to accurate non-equilibrium kinetics and numerical stability. Moreover the automatic time stepping has now properly been adjusted for the changed junction kinetics in the 'multi-obstacle' model, no longer slowing down respective simulations.

new boundary condition „wetting“

can now be defined on the basis of above „contact angle” functionality


new documentation

It took quite a long time and it was a substantial effort. Along with Version 6.0 we have prepared new user manuals. The distribution now comprises the following 5 volumes of the manual:

MICRESS® manual Vol.0: MICRESS® - phenomenological background
MICRESS® manual Vol.1: MICRESS® installation
MICRESS® manual Vol.2: running MICRESS®
MICRESS® manual Vol.3: MICRESS® post processing
MICRESS® manual Vol.4: MICRESS® examples


We do hope that these improvements will assist you in solving your problems and will continue to make MICRESS® a valuable tool for your research. For more details, please don’t hesitate to ask us, preferentially via this MICRESS®-Forum.


Yours

George

nokkikku
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Re: MICRESS 6.0 released

Post by nokkikku » Mon Nov 28, 2011 3:54 pm

Hi all,

I love the new documentation. Well done. :D

nokkikku

WTMuser
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Re: MICRESS 6.0 released

Post by WTMuser » Fri Feb 17, 2012 3:43 pm

Dear Sirs,

I have a question concerning the new functionalities and the treatment of "effective phases". Are two-phase regions (e.g. gamma / gamma_prime) replaced by a diffuse phase mixture automatically or should I modify the driving file? How can I visualize the shape of this "new" phase? Should I take "frac0" (liquid), "frac1" (fcc_a1) or "frac2" (gamma_prime) while using paraview?

Kind regards.
Martin

Bernd
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Re: MICRESS 6.0 released

Post by Bernd » Sat Feb 18, 2012 2:52 pm

Dear Martin,

the new effective phase model is invoked by putting the keyword "unresolved" as 2nd optional parameter in the same line with the seed phase number of the nucleation input. Then, the new seed will grow as an unresolved eutectoid mixture with the locally present grain of the substrate phase. This is only possible in case of nucleation on interfaces or triple junctions, because a substrate phase has to be defined.
For visualisation, the phase fractions may not be the best choice because they still refer to the original phases which are not constant inside the effective phase. For visualisation in MICRESS, the .orie output is especially useful because we implemented it such that, in case of an effective phase, it is showing the orientation of the nucleated phase, even if its phase fraction is below 0.5. For 3D visualisation, if you want to display isolines, it may be useful to create an extra output for the sum of the phase fractions of the two phases. This can be done using the "operations" facility of DP_MICRESS which allows creating new output files by arithmetic operations (look here). In this case, the operation would be simply
$1 + $2
if the two corresponding .frac outputs have been opened in the "operations" section of DP_MICRESS. Alternatively, one could use e.g. the mixture composition .conc of a gamma prime forming element like Al.

Bernd

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Re: MICRESS 6.0 released

Post by WTMuser » Thu Mar 29, 2012 8:02 pm

Dear Bernd,

I used the keyword "unresolved" to simulate the growth of eutectoid mixture (gamma / gamma_prime). Unfortunately the .orie output and the .frac2 output display no differences (see attached Figure). I would expect an increasing amount of eutectic by the use of "unresolved".

The .log file displays the following sentence.
Warning! Trailing characters in string: 2 unresolved

Thank you very much for your support.
Attachments
unresolved.jpg
unresolved.jpg (15.32 KiB) Viewed 4000 times

Bernd
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Re: MICRESS 6.0 released

Post by Bernd » Fri Mar 30, 2012 2:28 pm

Dear Martin,

according to the error message in the .log file, the input "unresolved" seems to be not recognized! The ultimate check is if you input a REAL value in the next line for the "Microstructure size" which is required by the "Effective Phase" model: Your code should stop there if the "unresolved" keyword was not recognized, because then the next input would be an INTEGER value!

If "unresolved" is not recognized it may be because you are using an older MICRESS version (5.*), or because you put the keyword somehow wrongly - the example file GammaAlphaPearlite_dri can be used as a reference. If you cannot find out the reason, please send me the input file, and I will try to find out...

Bernd

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Re: MICRESS 6.0 released

Post by WTMuser » Mon Apr 02, 2012 6:09 pm

Dear Bernd,

You are right. The keyword "unresolved" was placed at the wrong position. Placing the keyword in accordance to the example file GammaAlphaPearlite_dri the calculation runs without any warnings. But I have still two questions. The eutectoid mixture consists of phase 2 and phase 1 for the attached example? The mixture is composed of the new grain and the corresponding substrate?

# Number of types of seeds?
2
# Input for seed type 1:
# ----------------------
# Type of 'position' of the seeds?
# Options: bulk region interface triple quadruple [restrictive]
interface
# Phase of new grains?
2 unresolved
# Reference phase?
0
# Substrat phase [2nd phase in interface]?
# (for taking into account curvature undercooling, set to 0 to disable)
1

# Input for seed type 2:
# ----------------------
# Type of 'position' of the seeds?
# Options: bulk region interface triple quadruple [restrictive]
interface
# Phase of new grains?
1
# Reference phase?
0
# Substrat phase [2nd phase in interface]?
# (for taking into account curvature undercooling, set to 0 to disable)
2


Kind regards.
Martin

Bernd
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Re: MICRESS 6.0 released

Post by Bernd » Tue Apr 03, 2012 6:23 pm

Hi Martin,

It is correct what you say: If you define (in seed type 1) that phase 2 should be "unresolved", and the substrate phase is 1, then, upon nucleation, the grain of phase 1 which will be locally found will serve as partner for the new seed of phase2 to form a diffuse "pseudo-grain". The orientation of the "lamellar phase" 2 will be used for output in .orie.

Bernd

zhubq
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Re: MICRESS 6.0 released

Post by zhubq » Thu Oct 10, 2013 11:52 pm

Hi, Bernd

I am trying to use the new features of MICRESS. I have some questions.

what's multi-obstacle phase field equation?

How to use the option "effective phase"? What's special of it?
Previously, when I construct an effective phase, I just devised the thermodynamic data such as dS, slope, reference concentration by myself. Certainly, selection of their values are kind of arbitrary, and usually based on the thermodynamic data of the constituent phases of this effective phase.

Ben

Bernd
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Re: MICRESS 6.0 released

Post by Bernd » Fri Oct 11, 2013 12:16 pm

Hi Ben,

"multi_obstacle" means that additional higher-order triple-point terms are included in the PF equation such that the triple point angles are correctly matched in case of different interface energies. This also allows for simulation of wetting phenomena.

The main advantage of the "effective phase" model in MICRESS (compared to your previous approach) is that it is thermodynamically consistent: The effective phase is treated as phase mixture, and the phase fractions can vary locally. In your case, this internal degree of freedom is missing, so the "pseudo-phase diagram" approach can only be a crude approximation. Apart from that, the "effective phase" model in MICRESS is much easier to use, especially in multi-component systems! The higher resource requirements can be regarded as a disadvantage, as the effective phase region is treated as an extended triple-junction which increases the interface area and thus the computational effort.

How to use this option has been discussed above in this thread.

Best wishes

Bernd

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