Search found 32 matches

by janin
Thu Feb 27, 2020 4:09 pm
Forum: solid-solid phase transformations
Topic: Benchmark 2D single grain growth with square law
Replies: 2
Views: 1001

Re: Benchmark 2D single grain growth with square law

Hi Billy, first I like to comment that the shrinkage of a single round grain is one of the fundamental benchmarks provided in the Micress/example/benchmark folder under the name 'B007_1Grain_Shrinking_dri'. If you do not yet have this folder, you can download it from the Micress webpage https://micr...
by janin
Thu Jul 18, 2019 5:42 pm
Forum: solidification
Topic: Grain Input
Replies: 9
Views: 2409

Re: Grain Input

Good question! We still have to change it. When we first implemented random grain positioning, the critical radius did not yet exist. Later, when we introduced the critical radius, we couldn't agree how to define it in this case and postponed the problem. At present, the critical radius is still sim...
by janin
Wed Jan 23, 2019 9:16 pm
Forum: phase-field model
Topic: general Phase field equation for multi-obstacle potential
Replies: 4
Views: 2144

Re: general Phase field equation for multi-obstacle potential

1.) In this formulation, the mobility M_{\alpha \beta }^{\phi } denotes the physical mobility of an interface between two phases alpha and beta. We have writen the PF equation in a way that the parameters can easily be identified by matching to the Gibbs-Thomson equation. In the case of uncoupled gr...
by janin
Mon Jan 21, 2019 2:33 pm
Forum: phase-field model
Topic: general Phase field equation for multi-obstacle potential
Replies: 4
Views: 2144

Re: general Phase field equation for multi-obstacle potential

Hi Ali, the MPF equation currently implemented in Micress is essentially still the same as in the 2006 paper, apart from some small changes in the definition of the prefactors. The major difference bewtween the two formuations you cited is that in 1) gamma runs over all phases including alpha and be...
by janin
Wed Jan 09, 2019 1:15 pm
Forum: phase-field model
Topic: interpretation of the tetragonal anisotropy functions
Replies: 6
Views: 2213

Re: interpretation of the tetragonal anisotropy functions

I won't say that this statement can be generalized, but both the kinetic coefficient and the interfacial energy sigma depend on the specific crystal lattice and their anisotropy can commonly be described by very similar functions, e.g. for cubic systems in 2D we assume a_kin = 1 + delta_kin * cos (4...
by janin
Fri Dec 07, 2018 4:11 pm
Forum: phase-field model
Topic: interpretation of the tetragonal anisotropy functions
Replies: 6
Views: 2213

Re: interpretation of the tetragonal anisotropy functions

nx,ny,nz are the cartesian coordinates of the local interfacial normal vector transformed into the coordinate system of the anisotropic grain. They can be transformed into spherical coordinates by: nx = cos(phi) *sin(theta) ny = sin(phi)*sin(theta) nz = cos(theta) In 2d this reduces to: nx = sin(the...
by janin
Thu Dec 06, 2018 3:00 pm
Forum: phase-field model
Topic: interpretation of the tetragonal anisotropy functions
Replies: 6
Views: 2213

Re: interpretation of the tetragonal anisotropy functions

Hi Deepu, the tetragonal anisotropy is a 4-fold cosine function 1 + delta*cos(4*theta) which can be elongated in z-direction by an elangation factor. This means, you will get a cosine function with 1+ delta as maximum and 1-delta as minimun, if the elongation factor is 1. In the general case, the el...
by janin
Wed May 16, 2018 12:31 pm
Forum: phase-field model
Topic: FD correction
Replies: 3
Views: 1725

Re: FD correction

Hi Ali, you are right, the FD-correction approach was theoretically derived for two-phase systems only. The problem with multiple phases is that we don't have the analytical formulation of the phase-field profile within the junction areas. I spend a lot of time on this problem, but so far without su...
by janin
Sun Apr 08, 2018 11:00 pm
Forum: pre-processing
Topic: input of static anisotropy changed!
Replies: 17
Views: 7234

Re: input of static anisotropy changed!

Hi Kamal, you are perfectly right. These equations are wrong and I'm afraid these are not the only ones, because Volume0 of the manual has once been written by a student and unfortunately we never had time to review it. The original Gibbs-Thomson equation is written in terms of temperature: velocity...
by janin
Tue Feb 27, 2018 10:30 pm
Forum: solid-solid phase transformations
Topic: Orientation for acicular ferrite
Replies: 1
Views: 1094

Re: Orientation for acicular ferrite

The aciculare ferrite can nucleate in two different variants, because both variants are equivalent in cubic austenite.
If you want to obtain just one of the two variants you can reduce the symmetry of austenite from 'cubic' to 'tetragonal' or 'none'.
Regards,
Janin