solidification of Al-alloy ( interface adhesion)

dendritic solidification, eutectics, peritectics,....
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Xianyi Kuang
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solidification of Al-alloy ( interface adhesion)

Post by Xianyi Kuang » Sun Sep 12, 2021 2:16 pm

Dear Bernd

Thank you for your response to my previous question about the distribution of crystal nuclei.

I have used MICRESS to simulate the final solidified structure of the aluminum alloy. I hope it is an equiaxed grain, of course it turned out to be the case. However, there is a problem that the interface distinction between crystal grains is not obvious. If it is only a small part of the crystal grains, I would think that the phenomenon of maturation has only occurred. However, there are many crystal grains with interfacial adhesion. I have attached the pictures and driver files below. Looking forward to your reply.

Best wishes
Kuang Xianyi
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Aluminum alloy equiaxed crystal_in.txt
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p1.png
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Bernd
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Re: solidification of Al-alloy ( interface adhesion)

Post by Bernd » Mon Sep 13, 2021 3:05 pm

Dear Kuang Xianyi,

You certainly mean with "interface adhesion" that there is coalescence between the grains even before the intermetallic phases form. I agree that this is expected to come much later, or only in conjunction with secondary phase precipitation. However, coalescence is a phenomenon at or close to the atomistic scale, so you would need a very high grid resolution to be able to correctly predict it using phase-field methods.

For your purpose, I guess, it is not important to really predict coalescence, but to just shift "numerical" coalescence behind secondary phase precipitation. This should be possible by a relatively slight increase of grid resolution (reduction of the grid spacing Δx).

Please be aware that increasing grid resolution can easily lead to significantly longer simulation times. Thus, you should make some trials to find the optimum grid resolution for your case.

This kind of "numerical" coalescence appears when the liquid channels between the grains get smaller than the numerical interface thickness, so that the two solid-liquid interfaces start overlapping. Alternatively (or supplementary) to increasing the grid resolution, you also could try to reduce the numerical interface thickness in cells (very last input parameter of the .in-file). In my opinion, using 3 cells instead of 4 as interface thickness still would be sufficient (as long as you do not have a strong focus on anisotropy phenomena), and, in terms of absolute interface thickness and thus "numerical" coalescence, would correspond to a reduction of Δx from 1 µm to 0.75 µm.

Bernd

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