Impact of Alloying on Stacking Fault Energies in γ-TiAl

Applied Sciences

卷:7

Svea Mayer¹  David Holec¹  Helmut Clemens¹  Phillip Dumitraschkewitz¹ 

[1] Chair of Physical Metallurgy and Metallic Materials, Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben A-8700, Austria;

关键词: titanium aluminides;    stacking fault energies;    density functional theory;   

DOI  :  10.3390/app7111193

来源: DOAJ

【 摘 要 】

Microstructure and mechanical properties are key parameters influencing the performance of structural multi-phase alloys such as those based on intermetallic TiAl compounds. There, the main constituent, aγ -TiAl phase, is derived from a face-centered cubic structure. Consequently, the dissociation of dislocations and generation of stacking faults (SFs) are important factors contributing to the overall deformation behavior, as well as mechanical properties, such as tensile/creep strength and, most importantly, fracture elongation below the brittle-to-ductile transition temperature. In this work, SFs on the { 111 ) plane inγ -TiAl are revisited by means of ab initio calculations, finding their energies in agreement with previous reports. Subsequently, stacking fault energies are evaluated for eight ternary additions, namely group IVB–VIB elements, together with Ti off-stoichiometry. It is found that the energies of superlattice intrinsic SFs, anti-phase boundaries (APBs), as well as complex SFs decrease by 20–40% with respect to values in stoichiometricγ -TiAl once an alloying element X is present in the fault plane having thus a composition of Ti-50Al-12.5X. In addition, Mo, Ti and V stabilize the APB on the (111) plane, which is intrinsically unstable at 0K in stoichiometricγ -TiAl.

【 授权许可】

Unknown