Structure of Rapidly Quenched Al-Mn

We report electron-microscopy and high-resolution x-ray-scattering measurements of rapidly quenched ${\mathrm{Al}}_6$Mn. The electron-diffraction pattern shows icosahedral symmetry. Peaks in the x-ray-diffraction pattern can be indexed to a mixture of fcc Al and a phase whose reciprocal lattice is described by a sum of icosahedral vectors. The half-width of the sharpest x-ray peak is 0.01 ${\mathrm{\AA }}^{-1\mathrm{}}$. A comparison is made with current theories of quasicrystalline order.