Concerning the κ Phase of Al-Cr-Ni

The structure of a new hexagonal phase aluminium–chromium–nickel, of reported composition Al14.4Cr3.4Ni1.1, has recently been described and refined in space group P63; most of the atom sites were described as disordered between various pairs of metal atoms [Sato et al. (1997). Acta Cryst. C53, 1531–1533]. A simpler structure, in space group P63/m, leads to better refinement. In the revised structure most of the atom sites are ordered. There is no indication of Ni in any of these ordered sites, but one partially occupied site may contain Ni, octahedrally coordinated to six Al atoms. Disordering along a chain of four atoms, parallel to the c axis, prevents a determination of the exact chemical composition; the approximate cell contents are Al177Cr49Ni.