Short-range order in undercooled Co melts

Abstract

It was suggested in 1952 by Frank that an icosahedral short-rangeorder(SRO) should be energetically favourable in undercooled melts of systems consisting of atoms with a sphere-like geometrical symmetry. Although this idea is nearly 50 years old, there is still a lack of direct experimental information on the SRO prevailing in undercooled metallic liquids. In this work the results of investigations of the SRO of deeply undercooled liquids of Co by energydispersive diffraction of synchrotron radiation are presented. The experimentally determined structure factors were simulated by assuming that the liquid consists of clusters with different short-range structures. The best fit of the experimental data is obtained if an icosahedral SRO is assumed. Thus, our investigations strongly support Frank’s idea of an icosahedral SRO prevailing in undercooled metallic liquids.