XVI.The Brillouin Zones for theCo2Al9andNiAl3Structures

Abstract

The results described above indicate t h a t , for the intermediate phases Co2A1 , and NiA13, the most probable Brillouin Zones are characterized by inscribed spheres which can contain respectively 2-12 and 2.00 electrons per atom. These values are in close agreement with the values of 2-125 and 2.09 electrons per atom cMculated for these structures according to the theory of the r61e of transitional nletal solutes in aluminium-rich alloys developed in previous work. This work, combined with the observation of Mrs. Douglas t h a t in Co₂A1₉ the cobalt atoms possess of the order of 2 electrons in excess of their normM complement of 27, confirms that, in alunlinimn-rich alloys, transitionM metal atoms absorb electrons from the structure as a whole. The close quantitative agreement between the numbers of electrons per atom which correspond to the inscribed spheres of the Brillouin Zones and the numbers of electrons per atom calculated according to the absorption theory indicates t h a t the number of electrons absorbed per atom of a transitional metM cannot differ appreciably from the ,amber of vacancies per atom in its atomic orbitals.