MICRESS version 5.5 released 23.3.2010

new developments, future functionalities, hints for further applications of MICRESS
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admin
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MICRESS version 5.5 released 23.3.2010

Post by admin » Tue Mar 23, 2010 11:41 am

Dear MICRESS users,

the present version 5.5 of MICRESS® has been released today.It comprises a number of improvements with respect to input/output and performance as well as new functionalities. Of course we also attempted to fix all bugs reported by the user community.


Input/Output


new input: initial structures

The new release allows reading in initial microstructures using the vtk format. This is particularly useful for 3d structures.

new input: time dependant temperature profiles

Temperature profiles can now be read from file as time dependant 1-dimensional profiles.

extended .cphas output

the .cphas output has been modified and now allows also writing compositions of several phases simultaneously.

new output for grain information TabGD

The information about the grain status, i.e. whether a grain is still "small" or already "big" is now included into the .TabGD file.

extended input for elastic material data (elastic module only):

The input of elastic material data allows now the definition of material properties with reduced symmetry i.e. beyond isotropic or cubic.


New Functionalities


new feature: Paraequilibrium/NPLE

A new paraequilibrium and nple mode is available. It can be used for the redistribution of elements which have a diffusion length being much smaller than the interface thickness. Using standard interactions, MICRESS would predict a growth mode which lies between paraequilibrium and nple. The new release allows the two extreme cases of redistribution behaviour to be specifically requested.


new feature: dependant composition sets

In some phases two elements are located on the same sublattice (e.g. N and C in Ti(N,C)), so that their composition in the phase is directly dependent on each other. For such phases, the multi-binary extrapolation scheme of MICRESS is not optimal, because each component is calculated with respect to the matrix element which itself is nearly insoluble in such phases like above Carbonitrides. In this case, the new hidden expert option "dependent" may help, which applies a modified redistribution scheme.

new feature: second substrate phase

In multiphase simulations it may be not sufficient to specify only one substrate phase for interface nucleation. Imagine a gamma-alpha transformation with cementite: In order to create a nucleation type for cementite only on the fcc-fcc interface and not on all fcc interfaces with other phases, it is necessary to specify a second substrate phase. This feature is included in the new release.

new feature: infinite diffusion

A new option "infinite_restrictive" has been introduced to handle infinite diffusion in cases with multiple grains. Before this update, infinite diffusion was automatically solved for each grain but not in between the grains in case multiple grains of the respective phase were present. Now, the user has the choice to use "infinite" for mixing composition between all grains of the phase, and "infinite_restrictive" to apply infinite diffusion on each grain individually (and such to respect the neighbourships of the grains).


new feature: reset time

A new option has been introduced which allows resetting the time when using the restart option. If the restart option is used to simulate a process consisting of many steps (like solidification-heat treatment-cooling-aging), it can be quite difficult to have a single, consecutive time scale and to copy the overall temperature history into all process steps. With the new option reset_time it is possible to reset the time to zero. This feature also includes a reset for the complete relinearisation and update of the diffusion coefficients times.

new feature: Limits

Sometimes, while using thermodynamic databases, problems can occur which are related to the composition sets of a phase. During a MICRESS simulation it may happen, e.g. for numerical reasons, that the composition might switch to the wrong composition set. To prevent this undesired behavior, a new optional feature has been added, which permits to limit the allowed composition range of a phase.

new feature: linear TQ

The new release allows specifying linearized phase diagrams in two ways, the normal linear phase diagram as before (keyword "linear" in phase diagram input) and in form of complete linearization data as they are written into the MICRESS .log file (keyword "linearTQ").

new feature: global linearization

The use of global linearization parameters with thermodynamic coupling is now possible. This means one can use one set of linearization parameters per interface (of grain pair k1/k2) instead of one set of linearization parameter per interface cell. The main advantage of the global linearization is an enhanced performance and stability.

new feature: mixed use of linearized and database phase descriptions

Another new feature is particularly useful for the description of “effective phases” like e.g. pearlite, which do not have a description in the thermodynamic database and now can be added with own, linearized equilibrium descriptions in a mixed use of database and linearized data.


improved description of triple and higher order junctions

The new “multi-obstacle” mode now comprehensively takes into account all multiphase/multigrain interactions including higher order contributions at multiple junctions. These forces, which act at junctions where boundaries with different interfacial energies adjoin, are required to correctly simulate the contact angles. The “double-obstacle” approximation is still recommended for all applications, where accurate modeling of triple junctions is of minor importance as in general it is numerically more stable and much faster.

improved description of stoichiometric phases

The description of stoichiometric phases has been substantially improved. Phases without any solubility for certain elements are automatically assigned in case of TQ coupling. For other cases an explicit solubility can optionally be specified, improving the flexibility in the description of stoichiometric phases. An extra option “enhanced_stochiometric” is provided for improved extrapolation of the distribution behavior.

new temperature solver

In case of type of coupling „temperature“ the user now can select different iterative solvers, e.g. Gauß-Seidel, BICStab and others. Each of these solvers has its own pros and cons and the optimal choice in terms of performance will depend on the simulation example.

automatic time stepping

The stability criterion used for the evaluation of the automatic time step has been tightened in order to be safer when using the default time stepping factor of 1. The user can still manipulate the criterion by setting either smaller or larger factors.



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 forum


Yours

George

sunny
Posts: 22
Joined: Tue Jun 23, 2009 2:57 pm

Re: MICRESS version 5.5 released 23.3.2010

Post by sunny » Tue Mar 30, 2010 12:36 pm

Hi, George,

Thank you for your information!

I am interested in the new feature 'Limits', which should be useful to treat the order-disorder transition and miscibility gap cases. But now, could you show me how to use it in the .dri file?

Another issue is about the version of the TQ version in your new released MICRESS version, TQS or TQR? Can we directly use the atomic mobility for ordered phase, like 'Acta Materialia, Volume 50, Issue 4, 25 February 2002, Pages 775-792 '?

Best wishes!

yours,

sunny

Bernd
Posts: 1504
Joined: Mon Jun 23, 2008 9:29 pm

Re: MICRESS version 5.5 released 23.3.2010

Post by Bernd » Tue Mar 30, 2010 3:02 pm

Dear Sunny,

the use of the "Limits" feature is described in the same board as this thread:

"New Feature: Limits"

Please tell us about your experiences because this feature has not been often used up to now!

Unfortunately, the TQ version of the new release 5.5 is still TQ_R. TQ_S still shows severe instabilities, so that we could not include it yet. Hopefully we will get soon a stable version from TC AB.

You can directly use mobility data in MICRESS as long as they are provided in the correct .TDB format (like in the MOBNI database) and you include them into the .GES5 file using the Thermo-Calc software. Please make sure to use the TC version which corresponds to the TQ-version of MICRESS (TC_R for the time being).

Bernd

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