Lattice constant of martensite?

[erin85]

Hi everyone-

I am trying to run some MD simulations of martensitic iron. I am having a lot of trouble finding a lattice constant anywhere in the literature... I know the crystal structure is bct, so there will be some c/a ratio as well... any suggestions?

Erin

 

[erin85]

I have done a little bit more research... but I am not well versed enough in steels to figure out if what I am saying is true.

I want to research the transition from austenite (fcc) to martensite. The potential I am using was written for ferrite (bcc), with a lattice constant of 2.8553, but I think it will still be stable for austentite. Doing a lowest energy calculation, I figured out the lattice constant for fcc is about 3.66.

Now, if I am simulating pure Fe, with no carbon, is it correct that the martensite will have a bcc configuration? I believe the bct deformation is caused by carbon atoms not fitting in properly... if so, then I can create an interface between some fcc and bcc, and let it run, and this would effectively simulate a austenitic/martensitic boundary. Does this seem correct?

 

[Gokul43201]

I don't think you will find a useful c/a in literature because this is a strong function of composition and heat treatment (which means there's non-equilibrium weirdness hidden in it - probably from diffusion of C)!

The authoritative reference is supposed to be: Wechsler, M. S., Lieberman, D. S., and Read, T. A., “On the Theory of the Formation of Martensite,” AIME Trans. J. Metals 197, 1503 (1953).

If that's hard to access, try: S. Lieberman, M. S. Wechsler, and T. A. Read, J. Appl. Phys. 26, 473 (1955)