Short-range order in undercooled melts forming quasicrystals and approximants

For the first time, the short-range order of deeply undercooled liquids of alloys fort-ning quasicrystalline and polytetrahedral phases (Al13Fe4 and Al74Co26) is investigated by combining the containerless processing technique of electromagnetic levitation with elastic neutron scattering. The experimentally determined structure factor, S(Q), was simulated by assuming that clusters with different structures exist in the liquid. The best fit of the experimental data is obtained under the assumption of an icosahedral short-range order. This supports the nearly 50 year-old prediction of Frank that an icosahedral short-range order prevails in undercooled metallic liquids. (C) 2002 Elsevier Science B.V. All rights reserved.