ELECTRONIC-STRUCTURE ANALYSIS OF INTERMETALLICS FOR CRYSTAL-STRUCTURE CHANGES IN NB3AL

In order to improve the brittleness of Nb3Al, one interesting approach is to change its crystal structure to a higher symmetry in order to increase the available number of slip planes and thereby its plasticity. To obtain a guideline for crystal structure change from the aspect of chemical bonding, its electronic structure has been calculated by the molecular orbital method (extended Hueckel method). In addition, the effect of replacement of Nb with Zr or Mo in Nb3Al has been examined. The bond order, modified for dealing with a complex cluster, has been found to be effective for indicating the preference between possible crystal structures and the change of the Nb3Al crystal structure on replacing Nb with Zr.