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