Studies of aluminum-rich alloys with the transition metals manganese and tungsten. I. The crystal structure of ε(W-Al)-WAl₄

Abstract

The crystal structure of WAl/sub 4/ has been determined with moderate accuracy. The space-group symmetry was found to be Cm, and precision lattice parameters were measured as a = 5.272, b = 17.771, c = 5.218 A, BETA = 100 deg 12'. The heavy atom' technique was used to find the approximate structure, and F/sub 0/ syntheses were used in the refinement. The atomic arrangement is noncentrosymmetrical and the cell contains 30 atoms mostly confined to eight well- defined layers porpendicular to the b axis. There is a close similarity between the unit cells and structures of WAl/sub 4/, MnAl/sub 6/, and sigma (Mn- Al) -- Mn/sub 4/Al/sub 11/. (auth)