MICRESS Forum

Dear Bernd,

I have a question about how to determine interfacial energy and mobility in an anisotropic model.

In an anisotropic model, interfacial energy and mobility can be defined in two ways:
One is the "low-angle misorientation" function (based on the Read-Shockley and Humphreys law), and the other is the "anisotropy" function (as shown in Table 4 at the following URL):
https://docs.micress.de/7.3/micress/top ... anisotropy

For example, both functions are defined in the following code.
When the misorientation between grains is smaller than the low angle limit (in this case, 15 degrees), which function ("low-angle misorientation" or "anisotropy") is actually used to determine the interfacial energy and mobility?

# Shall misorientation be considered?
# Options: misorientation no_misorientation
# [low_angle_limit <degrees (default=15)>] [special_orient <nb>]
misorientation low_angle_limit 15
# Input of the misorientation coefficients:
# Modification of interfacial energy for low angle boundaries
# Options: factor read-shockley
read-shockley
# Modification of the mobility for low angle boundaries
# Options: {factor | humphreys [<minimum> <parameter B> <parameter N>]}
# (default: minimum=0.05 B=5.0 N=4.0)
humphreys
# Is interaction isotropic?
# Options: isotropic
# anisotropic [junction_force] [harmonic_expansion]
anisotropic
# This anisotropic interaction is not yet implemented.
# Instead: isotropic-metallic
# Anisotropy of interfacial stiffness? (cubic)
# 1 - delta * cos(4*phi), (delta =delta_stiffness =15*delta_energy)
# Coefficient delta (<1.) ?
0.1000000000000
# Anisotropy of interfacial mobility? (cubic)
# 1 + delta * cos(4*phi)
# Coefficient delta (<1.) ?
0.1000000000000

Best regards,
Chika

In general, the properties of interfaces between two solid phases are governed by five parameters:
Three parameters describing the rotation between the crystal lattices (in Micress referred to as 'misorientation'), and two parameters describing the orientation of the boundary plane (in Micress referred to as 'interface anisotropy)'.
In Micress, we model the two aspects by individual functions, one capturing the misorientation dependence, and the other describing the boundary plane orientation (anisotropy). The overall anisotropy factor is then calculated as the product of the two functions.
In grain growth simulations, the misorientation factor typically dominates. The anisotropy component becomes significant only in cases involving special orientation relationships—such as twin boundaries.These can be specified using the additional option 'special_orient'. When this option is active, the keyword 'aniso_special_orient' (instead of the standard 'anisotropic') allows users to define an anisotropy function that applies exclusively to interfaces with the designated special orientation relationship.

You can find the detailed description in the Micress documentation:
https://docs.micress.de/7.3/micress/inp ... rientation

With best regards,
Janin

Dear Janin,

Thank you so much for answering to my question.
I could understand the feature of each function.

Best regards,
Chika