MICRESS Training

solid-solid phase transformations, influence of stresses and strains
Post Reply
shaojielv
Posts: 100
Joined: Thu Apr 01, 2021 2:16 pm
anti_bot: 333

MICRESS Training

Post by shaojielv » Wed Jun 02, 2021 3:09 pm

Dear Bernd,
Hello, I met some problems in MICRESS and would like to consult you.The following questions arise in the process of case T014_gamma_alpha_stress:
1, in the program set up three solid phase, so it is the existence of the third solid phase in addition to γ and α phase, according to my understanding of the program these three phases are respectively: γ, α and pearlite (P), and here the pearlite is at 985K began to generate, I do not know my understanding is correct?The other thing I don't understand is why the third solid phase is set, or is the third solid phase set necessary?
2. In the absence of coupled Thermo-Calc, we use the linearization of the local phase diagram, but how do we define the reference points when there is a third solid phase (the position of the component in phase 1 and phase 3, respectively)?
3. At # Initial concentrations, Phases 0, 1, 2, and 3 are present.Why are there four phases?Where did phase 0 or phase 3 come from here?I really don't understand this.Also, for # Elastic Components, why are there only C11, C12, and C44?And then finally how did you calculate the molar volume for the phase?I don't understand these questions.I am looking forward to your reply very much, and I will appreciate it very much.

Finally, I sincerely wish you a happy life and smooth work.
Lv Shaojie

admin
Site Admin
Posts: 56
Joined: Fri Jun 13, 2008 4:03 pm

Topic has been shifted

Post by admin » Mon Jun 07, 2021 10:50 am

Dear user,

Your post has been shifted here because it does not fit to the board "MICRESS training".

Thank you for your understanding

Your administrator

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

Re: MICRESS Training

Post by Bernd » Mon Jun 07, 2021 11:28 am

Dear Lv Shaojie,

I will try to give answers to your questions:

1.) The training example T14 is already quite old and needs some rework. As far as I remember, the third phase should be cememtite, but given that the input file uses user-defined linearized phase diagram data, it also could resemble pearlite as a pseudo-phase. According to these user-defined thermodynamic data, the third phase is necessary because it gets stable during transformation of phase 1 to phase 2.
I agree that without further information it is impossible to know that, given that there are no comments, and the phases and elements are not named - you can only assume that on the basis of the example name and its similarity to the other MICRESS examples T10-T13...

2.) In a linearized phase diagram description for 3 or more phases, there is typically not a common reference point existing. That means, each pair-wise description is described independently, but must be consistent with the others, so that at triple junctions there is a three phase equilibrium without excess driving forces. This is difficult and often can be achieved only for one temperature. Generally, we recommend using TQ-coupling in such cases if possible.

3.) In MiCRESS, phase 0 has special properties because historically MICRESS was developed as a solidification tool. It resembles the liquid phase and cannot have anisotropic phase properties. Therefore, we have to include it in the simulation, even if it is not present anywhere. At some places, we also need to define fake properties for that reason.
Elastic constants consist only of the three components C11, C12 and C44 because cubic symmetry is assumed.
The molar volume can be either specified by the user based on literature, or can be obtained from a database when TQ-coupling is used (if the database includes molar volume data).

Best wishes
Bernd

Post Reply