Molecular dynamics simulation of displacement cascades in B2 NiAl

Abstract

This study is focused on the behavior of B2 NiAl alloy under irradiation. For achieving this aim, we performed a series of molecular dynamics simulations of displacement cascades with the primary knock-on atom (PKA) energy from 1 keV to 40 keV. To ensure that the boundary effects were not important, the simulation boxes contained from 60 × 60 × 60 to 112 ×112 ×112 unit cells with 432 000 to 2 809 856 atoms, depending on the PKA energy. To correctly reproduce atomic interactions at short distances, the Mishin EAM potentials were stiffened in a short range using polynomial regression to join the equilibrium part of the EAM potential to a short range of ZBL potential and intermediate interatomic distance with the corresponding pairwise energy based on the density function theory calculation. To obtain statistically meaningful results, 10 simulations were performed for each PKA energy. Each cascade simulation lasted approximately from 12 ps to 42 ps, depending on the PKA energy; in these time intervals the number of Frenkel pairs (FP) became stable. We discuss in detail the time evolution of Frenkel pairs, the avalanche effect in the sonic phase and the origin of the permanent defect. The results from our simulations, including the number of stable Frenkel pairs, chemical composition, clustering of the defect production are in good agreement with the reports from the literature.

Molecular dynamics simulations of displacement cascades in LiAlO 2 and LiAl 5 O 8 ceramics

“…Additionally, all simulations were carried out with a 5 Å thick Langevin bath maintained at 300 K to dissipate the heat generated by the high energy PKA. This thermostat had a signi cant role in limiting the maximum temperature rise during PKA initiation but had a negligible effect on the defect production due to the small fraction of atoms included in its volume 27 . The velocities of the atoms in the thermostat region were rescaled to the corresponding value at 300 K at every step so that this thermostat simulated the dissipation of heat energy from the cascade region into the bulk.…”

Упругие свойства B2-NiAl с добавлением W: исследование из первых принципов

“…Высокая температура плавления, широкая область гомогенности, высокая теплопроводность, низкая плотность позволяют использовать материалы на основе B2-NiAl в авиа-и ракетостроении, электронике. За счет высоких антикоррозийных свойств и отличных эксплуатационных характеристик в условиях высоких температур и давлений сплавы на основе никеля используются в современных ядерно-энергетических системах [1]. Одним из сдерживающих факторов в использовании B2-NiAl является низкая пластичность в крупнокристаллическом состоянии, отсутствие трещиностойкости при комнатной и низких температурах, а также недостаточная прочность при температурах выше 1100 • K. Охрупчивание этих сплавов можно уменьшить несколькими путями, в том числе микро-и макролегированием.…”

Elastic Properties of B2-NiAl with W addition: A first-principles study

“…High melting point, wide area of homogeneity, high thermal conductivity, low density allow the use of materials based on B2-NiAl in aircraft and rocket engineering, electronics. Due to the high anticorrosion properties and excellent performance at high temperatures and pressures, nickel-based alloys are used in modern nuclear power systems [1]. One of the limiting factors in the use of B2-NiAl is low plasticity in the coarse-crystalline state, lack of crack resistance at room and low temperatures, as well as insufficient strength at temperatures above 1100 • K. Embrittlement of these alloys can be reduced in several ways, including micro-and macroalloying.…”