ALLOYING EFFECT ON THE ELECTRONIC-STRUCTURES OF NB AND MO

The alloying effects on the electronic structure were investigated for both Nb-based and Mo-based alloys in order to obtain useful information for alloy design. The electric structure was calculated using the DV-Xalpha cluster method, and two alloying parameters, the bond order BO and the d-orbital energy level MD, were obtained for a variety of alloying elements M in these metals. The binary phase diagrams of the Nb-M and Mo-M systems were found to be classified according to the location in the BO-MD map. Also, with respect to the nature of the chemical bond between atoms, Nb and Mo were compared with the other BCC metals such as Ti, V, Cr, Fe and Zr. Furthermore, it was shown that the activation energy for atomic diffusion, the heat of fusion and the melting temperature could be associated with the bond order. These results will indeed give some guide to the design of these refractory-metal-based alloys for high-temperature applications.