Dear Sir/Madam,
I apologize for the interruption. I am attempting to develop a microstructure dominated by the FCC phase, so I have configured the model to favor FCC nucleation exclusively. However, the simulation results still indicate a BCC-dominated structure.
Is this behavior expected? Could you please advise on how I might improve my model to better promote FCC formation? Alternatively, could it be that under the current thermodynamic conditions, the FCC phase is not favorable?
The code is included in the attachment. Thank you for your time and patience. I look forward to your guidance.
Best regards,
Dai He
https://gigamove.rwth-aachen.de/en/down ... baa59916c5
Asking help for generating proper results
Re: Asking help for generating proper results
Dear Dai He,
Thank you for sharing your nice simulation results. Why are you sure that fcc should be more stable under these conditions? Is there any knowledge from experiments under similar conditions that fcc should dominate? It is clear that at high cooling rates the relative stability of fcc and bcc may shift compared to lower cooling rates. The reason is that at high solidification velocity the dendrite tips grow at lower temperature where thermodynamics are different. So I would not be astonished if the effect is real.
However, please be aware that the tip undercooling of dendrites is exaggerated in 2D-simulations, so that 3D-simulations may show a different picture.
I found an artifact in your simulation, which is a liquid-liquid phase-boundary that is of course not real. The reason is an error in the nucleation conditions for the melt which create a liquid phase with grain number 0. However, in your initial microstructure from the restart file the grain number of the liquid phase is 2. You should change the grain number of nucleating liquid to 2 also (or start from a completely solid initial microstrurcture). The liquid-liquid grain boundary is visible in the .intf-output and disturbs the growing bcc dendrites. But I don't believe that this has an effect on the prevailing phase.
Best wishes
Bernd
Thank you for sharing your nice simulation results. Why are you sure that fcc should be more stable under these conditions? Is there any knowledge from experiments under similar conditions that fcc should dominate? It is clear that at high cooling rates the relative stability of fcc and bcc may shift compared to lower cooling rates. The reason is that at high solidification velocity the dendrite tips grow at lower temperature where thermodynamics are different. So I would not be astonished if the effect is real.
However, please be aware that the tip undercooling of dendrites is exaggerated in 2D-simulations, so that 3D-simulations may show a different picture.
I found an artifact in your simulation, which is a liquid-liquid phase-boundary that is of course not real. The reason is an error in the nucleation conditions for the melt which create a liquid phase with grain number 0. However, in your initial microstructure from the restart file the grain number of the liquid phase is 2. You should change the grain number of nucleating liquid to 2 also (or start from a completely solid initial microstrurcture). The liquid-liquid grain boundary is visible in the .intf-output and disturbs the growing bcc dendrites. But I don't believe that this has an effect on the prevailing phase.
Best wishes
Bernd