Characteristics
Rhenium is a silvery-white metal with one of the highest melting points of all elements, exceeded by only tungsten and carbon. It is also one of the densest, exceeded only by platinum, iridium and osmium. Rhenium has a hexagonal close-packed crystal structure, with lattice parameters a = 276.1 pm and c = 445.6 pm.
Its usual commercial form is a powder, but this element can be consolidated by pressing and sintering in a vacuum or hydrogen atmosphere. This procedure yields a compact solid having a density above 90% of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, or rolled. Rhenium-molybdenum alloys are superconductive at 10 K; tungsten-rhenium alloys are also superconductive around 4–8 K, depending on the alloy. Rhenium metal superconducts at 1.697 ± 0.006 K.
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