{\omega} structure in steel: a first-principles study
  Recent experimental works reported observation of the {\omega} structure in steel. Here, stability of the {\omega} structure in steel is investigated based on first-principles with special interests in effects of interstitial C atoms. The interstitial C atoms increase the energy of the {\omega} structure compared with the ferromagnetic (FM) BCC. The {\omega} structure incorporating C atoms is also mechanically unstable unless the C concentration is 25 at.%. It is concluded that the {\omega} structure is mostly unstable in steel, and the {\omega} structure in steel may be formed under special atomic constraints at twin boundaries or other interfaces. 
Yuji Ikeda, Isao Tanaka
cond-mat.mtrl-sci