Hallo Bernd,
I heard that paraequilibrium (PE) in MICRESS is a 'forced' condition. So the iteration will start without PE and then the element concentration will be forced to change according to the PE condition. Is it right?
So if I run a simulation with PE, would you suggest me to activate the diffusion of all the substitutional solute elements?
Thanks
nokkikku
Paraequilibrium in MICRESS
Re: Paraequilibrium in MICRESS
HI nokkikku,
I am not sure whether I understand what you mean by "forced" condition. PE defines a certain condition for redistribution of (typically) substituional elements in that way that they are not redistibuted and therefore do not reduce the total driving force of the phase tronsformation. The condition is "forced", otherwise it would not be a condition
The question whether it makes sense to define a finite diffusion for those element is more easy to answer: Normally, as the diffusion length of those elements is very small under PE conditions compared to the interface thickness, diffusion is so slow that it does not have any effect on the phase transformation. In so far, there is no reason to define them, but it would also not hurt (as long as we don't consider performance).
There may exist cases where it nevertheless would make sense to define these diffusion coefficient, like when a subsequent heat treatment is to be simulated or temperature is increased substanitally.
Diffusion and redistribution are two distinct processes in MICRESS: Whether an element is redistributed or not will not change the (mixture) concentration distribution (.concX), as long as there is no diffusion. It will only change the driving-force which depends on the phase compositions (.XPhay)!
Bernd
I am not sure whether I understand what you mean by "forced" condition. PE defines a certain condition for redistribution of (typically) substituional elements in that way that they are not redistibuted and therefore do not reduce the total driving force of the phase tronsformation. The condition is "forced", otherwise it would not be a condition
The question whether it makes sense to define a finite diffusion for those element is more easy to answer: Normally, as the diffusion length of those elements is very small under PE conditions compared to the interface thickness, diffusion is so slow that it does not have any effect on the phase transformation. In so far, there is no reason to define them, but it would also not hurt (as long as we don't consider performance).
There may exist cases where it nevertheless would make sense to define these diffusion coefficient, like when a subsequent heat treatment is to be simulated or temperature is increased substanitally.
Diffusion and redistribution are two distinct processes in MICRESS: Whether an element is redistributed or not will not change the (mixture) concentration distribution (.concX), as long as there is no diffusion. It will only change the driving-force which depends on the phase compositions (.XPhay)!
Bernd
Re: Paraequilibrium in MICRESS
Hi Bernd,
very nice answer. So I will continue the simulation without finite diffusion for PE. I reallised it saves some time.
nokkikku
very nice answer. So I will continue the simulation without finite diffusion for PE. I reallised it saves some time.
nokkikku