The elastic and plastic properties, generalized stacking-fault energy, surface energy, and electronic properties of AlxFeCuCrNi high-entropy alloys are studied via first-principle calculations. The present work is performed by employing density-functional theory within the general gradient approximation and virtual crystal approximation model. The increasing Al concentration enhances Young's modulus, bulk modulus and shear modulus, but it reduces the ductility based on the investigation of Cauchy pressure, ratio between shear modulus and bulk modulus, and Poisson's ratio. Besides, all AlxFeCuCrNi (0.1 ≤ x ≤ 1) high-entropy alloys are elastic anisotropic materials. In addition, the high Al concentration results in the large generalized stacking-fault energy and surface energy in AlxFeCuCrNi high-entropy alloys, which cause the possibility of dislocation nucleation and the inhibition of nanocrack formation.

Effect of Al solute concentration on mechanical properties of AlxFeCuCrNi high-entropy alloys: A first-principles study

Magnetic, magnetocaloric and structural properties of manganese based monoborides doped with iron and cobalt – A candidate for thermomagnetic generators

Structure and magnetic properties of the 3d transition-metal mono-borides TM-B (TM=Mn, Fe, Co) under pressures

An investigation concerning generalized stacking fault behavior of AlCoxCrFeNi (0.25 ≤ x ≤ 2) high entropy alloys: Insights from first-principles study

In this paper, spin and non-spin polarization (SP, NSP) are performed to study structural properties and bond hardness of Fe
 x
 B (x = 1, 2, 3) compounds using density functional theory (DFT) within generalized gradient approximation (GGA) to evaluate the effect of spin polarization on these properties. The non-spin-polarization results show that the non-magnetic state (NM) is less stable thermodynamically for Fe
 x
 B compounds than spin-polarization by the calculated cohesive energy and formation enthalpy. Spin-polarization calculations show that ferromagnetic state (FM) is stable for Fe
 x
 B structures and carry magnetic moment of 1.12, 1.83 and 2.03 μB in FeB, Fe2B and Fe3B, respectively. The calculated lattice parameters, bulk modulus and magnetic moments agree well with experimental and other theoretical results. Significant differences in volume and in bulk modulus were found between the ferromagnetic and non-magnetic cases, i.e., 6.8, 32.8%, respectively. We predict the critical pressure between ferromagnetic and non-magnetic phases. The model for hardness calculation using Mulliken population coupled to semi-empirical hardness theory proved effective in hardness prediction for the metal borides which agree well with the experimental values. These results would help to gain insight into the spin-polarized effect on the structural and bond hardness.

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Effect of spin polarization on the structural properties and bond hardness of Fe x B (x = 1, 2, 3) compounds first-principles study

Calculations of magnetism are made on transition metal monoboride of Fe ( 1 - x ) Co x B , with the scale 0 ⩽ x ⩽ 1 . In this paper, we calculate the ferromagnetic variation of transition metal monoboride by the method of virtual crystal approximation (VCA), based on density-functional theory (DFT) with generalized gradient approximation (GGA). The variations of ferromagnetism of Fe ( 1 - x ) Co x B alloys by the first-principle spin-polarized calculations are in agreement with experimental results, the prediction of the Stoner model and the Korringa–Kohn–Rostoker (KKR) method with coherent potential approximation (CPA). The spontaneous magnetization decreases with increasing x and vanishes at around x = 0.85 . This complies with earlier findings. The instability at around x = 0.8 is elucidated by electron filling of the Fe 3d orbital both from valence and interstitial electrons.

K.L. Chen

Papers

The magnetism of Fe(1-x)CoxB alloys: First principle calculations