Structures of Metals and Alloys at High Pressures

Abstract

A review is given on the results of the structural studies of metals and alloys subjected to high pressures. Transition metals exhibit high resistance against compression and keep their atomic arrangements unchanged. An exception is found in iron, which undergoes a transition from the bcc to hcp-structure. Rare-earth metals have larger compressibility and their crystal structures change systematically following the sequence hcp→Sm-type→dbcp→fcc. Simple metals have still larger compressibility, but some of their crystal structures remain stable while the others show a variety of changes. In actinoid metals, only americium has a number of high-pressure polymorphs. Many of the Hume-Rothery alloys and L1₀-type alloys are stable under compression, whereas pressure significantly affects the stability of the long-period ordered alloy structures. Pressure-induced transition of amorphous alloys leads to the formation of new crystal structures.