Strengthening effects of alloying elements W and Re on Ni3Al: A first-principles study.

The structural stabilities, mechanical and thermodynamic properties of pure and alloyed Ni 3 Al systems have been investigated systematically, based on density functional theory and Debye-Grüneisen model. Close attentions are paid to alloying elements W and Re by studying the strengthening effects of single-alloying element W, Re, Mo, Ta, Ru and co-alloying elements WRe, WMo, ReMo, WTa, ReTa, WRu, ReRu, which substitute the Al site and the nearest neighboring Al-Al sites, respectively. The calculated formation energies and elastic constants show that all the alloyed Ni 3 Al are thermodynamically and mechanically stable. It is found that alloying elements W has similar effects on the mechanical and thermodynamic properties of Ni 3 Al to those of Re, which suggests a possibility of replacing Re with W in Ni-based single crystal superalloys. In addition, co-alloyings with different elements have no distinct synergistic enhancement but simple combined effect on the mechanical properties of Ni 3 Al. The enhanced chemical bondings between the alloying atoms W/Re and the neighboring host atoms Ni are considered to be the main strengthening mechanisms in W/Re alloyed Ni 3 Al systems. [ABSTRACT FROM AUTHOR]