Theoretical study on site preference of Mn in B-containing Ni3Al alloys and elastic properties

gamma '-Ni3Al is the key strengthening element of nickel-based superalloys. Adding alloying elements can improve elastic properties of Ni3Al. Therefore, investigating the occupancy behavior of alloying elements in Ni3Al is very important to unravel their influence on the elastic properties of Ni3Al. In this work, the first-principles plane wave pseudopotential method combined with Wagner-Schottky model is used to explore the occupancy behavior of Mn in B-doped gamma '- Ni3Al. It is shown that B always occupies the octahedral interstices of Ni3Al regardless of alloy composition and temperature. At 0 K, Mn has no obvious occupancy tendency in pure and B-doped Ni3Al. With the increase of temperature, the tendency of Mn occupying the Al sites increases in stoichiometric and Al -rich alloys while it decreases in Ni-rich alloys. B doping can suppress the occupancy reversal of Mn in Ni3Al induced by temperature. The analysis of elastic properties reveals that the ductility of alloys can be improved by B or/and Mn co-doping. In particular, synergistic alloying of B and Mn can evidently enhance the ductility of Ni3Al alloys. Such synergistic effect demonstrates promising potential applications of Ni-based superalloys in extreme mechanical environments by adjusting alloy composition and alloying elements.

Automated summary

This study investigated the occupancy behavior of Mn in B-doped γ'-Ni3Al using first-principles calculations and experimental analysis, and revealed the influence of co-doping B and Mn on the elastic properties of the alloy. The results showed that B always occupied the octahedral interstices of Ni3Al, while the occupancy behavior of Mn varied with alloy composition and temperature. It was also found that co-doping B and Mn can enhance the ductility of the alloy, suggesting the potential applications of Ni-based superalloys in extreme mechanical environments through alloy composition and alloying elements adjustments.