Elastic, Electronic and Vibrational Properties of Ir-based Refractory Superalloys

Özet

The mechanical, electronic and vibrational properties of Ir-based refractory superalloys (Ir3Hf and Ir3Nb) in the L12 structure were studied in the framework of ab initio calculations. The obtained equilibrium lattice constants and bulk modulus were reported and compared with the existing data. The elastic constants of alloys were determined using energy strain method. The results were utilised to evaluate mechanical stability of alloys in the crystal structure of L12. Both alloys were found to be mechanically stable based on the Pugh’s criteria. Subsequently, electronic band structures and partial and total densities of states have been obtained for Ir3Hf and Ir3Nb. The band structures of alloys demonstrated metallic behaviour whilst the conductivity was mostly governed by Ir 5d states for both alloys. Moreover, phonon distribution curves of both alloys were obtained by employing the linear response technique within the density functional theory. Both alloys are found to be dynamically stable based on phonon modes evaluation.