About the input for "volume" and "matrix"
Posted: Tue Oct 22, 2013 6:37 pm
Hi,I am now simulating the case that one single grain of B2_Bcc phase precipitates from the matrix Fcc_A1 phase and the elastic strain is considered.
the lattice constant for B2_Bcc phase is a=0.287nm, molar volume is V=7.7746cm3/mol, the lattice constant for fcc_a1 phase is a=0.3552nm,
molar volume is V=6.7446cm3/mol.
As shown in the following, there are some input for "Eigenstrain", the "volume" and "matrix" , I have tried the two input repectly,
...
# Notation for Eigenstrain?
# Options: volume matrix
volume
# Abstraction of the 3D continuum
# Options: plane_stress plane_strain
plane_strain
...
If I choose "volume" , the molar volume of each phase should be input, and the grain will grow up to achieve equilibrium, the chemical driving force and elastic driving force are show in fig.1, their value are all in normal level, and the absolute value of chemical driving force is larger than elastic driving force.
If I choose "matrix" , three lattice misfit value of each phase should be input for "line", the calculated lattice misfit value according to
"(a(precipitate)-a(matrix))/a(matrix)" is " -0.192 " , which value is so large, the grain shrinked,which is not expected, the chemical driving force and elastic driving force are show n in fig.2, their value are abnormal, and the absolute value of chemical driving force is much less than elastic driving force,which lead to the shrinking process.
So my questions are as following,
(1) What's the difference between the two input for "volume" and "matrix",such as the calculating methods , assumption , for what condition they are applied, how can we choose them appropriately?
(2) Could you give me some help or interpretation about the above totally different results for grain growth by choosing "volume" and "matrix"? And for this condition which one do you recommend me to use?
(3) What's the difference between the "plane stress" and "plane strain"?
(4) Another question,we need to determine the number of matrix phase at the beginning, if there are multi-phase in the simulation, there may be one more different matrix phase, as for the present MICRESS code, how could we input two or more matrix phase number??,usually, we can only determine one phase number as Matrix,so if more, how to???
the lattice constant for B2_Bcc phase is a=0.287nm, molar volume is V=7.7746cm3/mol, the lattice constant for fcc_a1 phase is a=0.3552nm,
molar volume is V=6.7446cm3/mol.
As shown in the following, there are some input for "Eigenstrain", the "volume" and "matrix" , I have tried the two input repectly,
...
# Notation for Eigenstrain?
# Options: volume matrix
volume
# Abstraction of the 3D continuum
# Options: plane_stress plane_strain
plane_strain
...
If I choose "volume" , the molar volume of each phase should be input, and the grain will grow up to achieve equilibrium, the chemical driving force and elastic driving force are show in fig.1, their value are all in normal level, and the absolute value of chemical driving force is larger than elastic driving force.
If I choose "matrix" , three lattice misfit value of each phase should be input for "line", the calculated lattice misfit value according to
"(a(precipitate)-a(matrix))/a(matrix)" is " -0.192 " , which value is so large, the grain shrinked,which is not expected, the chemical driving force and elastic driving force are show n in fig.2, their value are abnormal, and the absolute value of chemical driving force is much less than elastic driving force,which lead to the shrinking process.
So my questions are as following,
(1) What's the difference between the two input for "volume" and "matrix",such as the calculating methods , assumption , for what condition they are applied, how can we choose them appropriately?
(2) Could you give me some help or interpretation about the above totally different results for grain growth by choosing "volume" and "matrix"? And for this condition which one do you recommend me to use?
(3) What's the difference between the "plane stress" and "plane strain"?
(4) Another question,we need to determine the number of matrix phase at the beginning, if there are multi-phase in the simulation, there may be one more different matrix phase, as for the present MICRESS code, how could we input two or more matrix phase number??,usually, we can only determine one phase number as Matrix,so if more, how to???