Site preferences and effects of X (X = Mn, Fe, Co, Cu) on the properties of NiAl: A first-principles study

Abstract

The site preference of X (X = Mn, Fe, Co, Cu) in NiAl and its effects on structural, electronic and elastic properties were investigated by performing first-principles calculations using density functional theory (DFT). Formation enthalpy calculations show that adding X increases the formation enthalpy of NiAl, indicating that X addition reduces the stability of system. The site preference was investigated by calculating the transfer energy of NiAl alloys with X. The results further exhibit that Mn, Fe and Cu show no site preference, but Co tends to occupy Ni site. By analyzing electronic density of states, Mulliken population, overlap population and valence charge density, the electronic property and bond characters were discussed. The elastic property calculation shows that only substitution of Ni by Cu increased the plasticity of alloy, while in the other cases the plasticity was decreased.

Microstructure and Mechanical Properties of BCC-FCC Eutectics in Ternary, Quaternary and Quinary Alloys From the Al-Co-Cr-Fe-Ni System

“…These findings are consistent with literature data: Duncan et al used atom probe field ion microscopy to show Fe preferentially occupying Al sites in NiAl (Duncan et al, 1994). Other studies found Cr clearly preferring Al sites (Medvedeva et al, 1998), while Co is found on the Ni sites, which is to be expected from the chemical similarity of the two elements (Li et al, 2016). It has to be noted that all these studies were conducted for very low concentrations of the substituting elements (Jones, 2003).…”

Site preference of Ti and Nb in L12-ordered Co-Al-W phase and their effect on the properties of the alloy: first-principles study

“…Doping Ti and Nb has little effect on Co and W atoms, but has a great effect on Al atoms, for the density of states. In figure 2(b), the DOS value of Al atoms in the system with Ti occupying the W 6 site is greater than that in the system with Ti doped in the Al 2 site, indicating that the former system is more stable [40], which is consistent with the previous result that is acquired from the formation enthalpy. In addition, the pseudogap of the former is narrower than that of the latter, which reveals that the bond of the former is more metallic than the latter [38].…”

First-principles calculations of structural, elastic and electronic properties of (TaNb)0.67(HfZrTi)0.33 high-entropy alloy under high pressure

“…The brittle-ductile behaviors of materials can be evaluated based on their calculated polycrystalline elastic properties. The intrinsic ductility and brittleness of materials can be predicted using an important comprehensive criterion that includes the ratio of bulk modulus to shear modulus B/G, Poisson's ratio ν, and the Cauchy pressure C 12 -C 44 [31][32][33]. Usually, a ductile material can be obtained when B/G > 1.75, ν > 0.26, and C 12 -C 44 > 0 are concurrently satisfied.…”