Effect of antiphase boundaries on the electronic structure and bonding character of intermetallic systems: NiAl

摘要: The possible origin of the high degree brittleness, i.e., low ductility, NiAl-based alloys in B2 structure is investigated by all-electron self-consistent total-energy linear-muffin-tin-orbital calculations. Using a supercell approach (with up to 20 atoms/unit cell), energetics two simplest antiphase boundaries (APB's) for NiAl structure--namely 1/2〈111〉 on {110} and {112}--are calculated assuming no relaxation at interface. We find APB energies order 800 mJ/${\mathrm{m}}^{2}$ both cases. Since are very high, 〈111〉 slip unlikely occur--as suggested experimentally some phenomenological theories. By substituting Ni or Al with V, Cr, Mn interfacial planes, remarkably decreased obtained. These theoretical results simplified model systems may suggest way decrease energy eliminate one reasons brittleness ambient temperatures.