%0 journal article
%@ 0255-5476
%A Pyczak, F.,Kononikhina, V.,Stark, A.

%D 2021
%J Materials Science Forum
%N 5
%P 1159-1165 
%R doi:10.4028/www.scientific.net/MSF.1016.1159
%T Stability of Ordered B2-βO and Disordered BCC-β Phases in Tial - A First Principles Study
%U https://doi.org/10.4028/www.scientific.net/MSF.1016.1159
5 
%X Either at higher temperatures or when a certain alloying element content is exceeded, γ-TiAl alloys contain the β phase (bcc) or its ordered derivate βo (B2). The relatively soft β phase can facilitate hot deformation, but βo is detrimental for creep strength and ductility. Thus, knowledge about βo→β phase transformation is desirable. Surprisingly, even for the binary Ti-Al system it is under discussion whether the ordered βo phase exists. Also, the effect of alloying elements on the β phase ordering is still unclear. In the present work the ordering of the β phase in binary Ti-(39,42,45)Al and ternary Ti-42Al-2X alloys (X=Fe, Cr, Nb, Ta, Mo) which was experimentally investigated by neutron and high energy X-ray diffraction is compared with the results of first principles calculations using density functional theory. Except for Cr the experimentally determined and the predicted behavior correspond.