First‐principles calculations of thermodynamic properties and planar fault energies in Co₃X and Ni₃X L1₂ compounds

Abstract

We do Density Functional Theory based total‐energy calculations of the normalL12 phase in Co3X and Ni3X compounds, X being a transition metal element. The lattice parameters, magnetic moments and formation enthalpies are determined and compared with the available experimental data. The (111) superlattice intrinsic stacking fault energy (SISF), a crucial factor affecting materials strength and their mechanical behavior, is calculated using the axial interaction model. We have applied the quasiharmonic Debye model in conjunction with first‐principles in order to establish the temperature dependence of the lattice parameters and the (111) SISF energies. We investigate our prediction of a low formation enthalpy in the system Ni −25 at.%Zn by doing auxiliary simulations for the fcc random alloy at the composition 25 at.%Zn. Our simulations indicate that the elements Ti, Zr, Hf, Nb, and Ta can help stabilizing the promising and extremely important Co3Al0.5W0.5 alloy.

First-principles modeling of superlattice intrinsic stacking fault energies in Ni3Al based alloys

“…One can notice that the decrease of SISF energy as a function of temperature is observed in the whole studied systems. Interestingly, we have recently [33] predicted similar decrease behavior of the SISF energies in the L1 at 1000 K for the composition 18.51825 at. %Pt, this gives rise to a reduction as big as ∼ 19 %.…”

“…Therefore their studied systems lack the realistic representation of chemical disorder and subsequently cannot be regarded as random solid solutions. The detailed methodology of the AIM is explained elsewhere [13,16,33]. There are two implementations of the AIM: the axial nearest-neighbor Ising model (ANNI) and the axial next-nearest-neighbor Ising model (ANNNI).…”

Trimetallic Catalyst Configuration for Syngas Production

“…The local nature of EXAFS on the other hand does allow to identify compounds in which Ni and Fe can be present. The ~3.50 � 0.02 Å value lies very close to the one reported by Breidi and et al, 3.556 Å, for a Ni 3 Fe bimetallic alloy [28] and to the ASTM reported value for FeNi 3 , 3.5523 Å (PDF 03-065-3244). The difference could be attributed to the nanosized dimension of the present supported nanoparticles, inducing a contraction of the alloy lattice.…”

“…ChemCatChem constant of 3.556 Å as lower reference point and 3.803 Å for metallic Rh as upper limit. [28] However, apart from the support material, no other crystalline phases are discerned for the reduced state, in particular no Ni, Fe or NiÀ Fe alloy phase (Table 2). Subsequent CO 2 -reoxidation again changes the crystalline composition of NiFe4Rh.…”

Generalised stacking fault energy of Ni-Al and Co-Al-W superalloys: Density-functional theory calculations

“…Calculations were performed at the Imperial College Research Computing Service, doi:10.14469/hpc/2232. Tables 2,(1−3 [74] 560 [13] 120 [13] -95 [13] Co 3 Ti 3.575 245 367 239 3.601 [73] 3.572 [75] 208 [75] Co [75] 1190 [13] 658 [13] -132 [13] [73] 223 [47] 172 [47] 79 [47] 3.572 (E) [77] 187 [72] 172 [72] 37 [72] Ni…”