First-principle calculations of structural, elastic and thermodynamic properties of Fe–B compounds

• DOI: 10.1016/j.intermet.2013.11.007
• Publication Date: 2013-12-10T11:30:50Z
• Authors: Liu-Hui Li; Wei-Li Wang; Liang Hu; Bing-Bo Wei
• Keywords: Orthorhombic crystal system; Vickers hardness test; Tetrahedron

Abstract The structural, elastic and thermodynamic properties of FeB, Fe 2 B, orthorhombic and tetrahedral Fe 3 B, FeB 2 and FeB 4 iron borides are investigated by first-principle calculations. The elastic constants and polycrystalline elastic moduli of Fe–B compounds are usually large especially for FeB 2 and FeB 4 , whose maximum elastic constant exceeds 700 GPa. All of the six compounds are mechanically stable. The Vickers hardness of FeB 2 is estimated to be 31.4 GPa. Fe 2 B and FeB 2 are almost isotropic, while the other four compounds have certain degree of anisotropy. Thermodynamic properties of Fe–B compounds can be accurately predicted through quasi-harmonic approximation by taking the vibrational and electronic contributions into account. Orthorhombic Fe 3 B is more stable than tetrahedral one and the phase transition pressure is estimated to be 8.3 GPa.