Stability, electronic and mechanical properties of Fe2B

In this paper, the stability, electronic and mechanical properties of three polymorphs of Fe2B were studied using CASTEP code. The calculated binding energy and formation energy values showed that Tp(2) (Space group, 1 (4) over bar 2m) and Tp(3) (Space group, 1 (4) over bar /mcm) structures of Fe2B are more stable than T-p1, (1 (4) over bar 2m). Structural analysis results indicated that Tp(2) and Tp(3) have the same atom coordinate numbers. Electronic structure calculations revealed that both Tp(2) and Tp(3) have very similar chemical bonding states, the d orbital splitting reduced DOS density at Fermi surface result in total energy reduction when compared with that of T-p1, and is consistent with thermodynamical results. The covalent bonds in these structures are due to orbital overlap between p bands of B and d bands of Fe, but the whole system has a metallic character and DOS at Fermi level are dominated by d bands of Iron. Elastic constants were also evaluated and indicated that in order to improve the abrasive property of boron casting irons; T-p1 is better than the other two structures and has the largest bulk modulus and Young modulus values. (c) 2007 Published by Elsevier B.V.