Metallurgy of Quasicrystals

Abstract

Discovered in 1984 (Shechtman et al. 1984), icosahedral (i) quasicrystals (QCs) exhibit a forbidden fivefold diffraction pattern with sharp diffraction peaks indicating the presence of a long range-order similar to the one of crystals. This discovery has stimulated interactions between scientists from many different fields. Intense efforts over the last decade by scientists dedicated to QCs have firmly established this new form of solid in solid state physics. Since QCs are found in metallic alloys, metallurgy plays an important role in this field. Great progress has been made by the discovery of new and highly perfect QCs. We now have a better understanding of QCs which leads us to address some very basic issues concerning QCs. QCs with structural quality comparable to single-grain silicon have been discovered. Like crystalline solids, QCs have several kinds of lattices and like intermetallic compounds, QCs are synthesized from different groups of elements with different chemistry. As a result, the name “quasicrystal” has been included as a new form of solid for the first time in a text book of solid state physics (Kittel 1995).In this article, I shall describe results obtained in the last decade and some aspects of QCs that have been of particular importance to the metallurgical community.