FORMATION OF ICOSAHEDRAL Al-TRANSITION METAL ALLOYS.

There has been considerable interest in rapidly solidified Al//8//6Mn//1//4 since a recent report by Shechtman et al. that this alloy exhibits icosahedral symmetry. Shechtman et al. have reported the same structure for rapidly soldified Al//8//6Cr//1//4 and Al//8//6Fe//1//4. As we show this structure is by no means limited to these alloys but is a common feature of rapidly solidified Al-transition metal alloys of the approximate stoichiometry of 6:1. Alloys of the composition Al//8//6T//1//4 with T equals Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Mo have been quenched from the melt at a rate of approximately 2 multiplied by 10**6 K s** minus **1 on the surface of a 15 cm diam Cu roller. Resulting ribbons were approximately 10 to 15 mu m thick by 1 to 2 mm wide. Depending on the alloy, ribbons from a few cm to a few m long were obtained.