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Osmium is a hard, brittle, blue-gray metal, and the densest stable element—about twice as dense as lead. The density of osmium is slightly greater than that of iridium ; the two are so similar (22.587 versus 22.562 g/cm 3 at 20 °C) that each was at one time considered to be the densest element.
Osmium is a hard but brittle metal that remains lustrous even at high temperatures. It has a very low compressibility. Correspondingly, its bulk modulus is extremely high, reported between 395 and 462 GPa, which rivals that of diamond (443 GPa). The hardness of osmium is moderately high at 4 GPa.
It has a chemical composition of 6% aluminum, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium. [19] It is significantly stronger than commercially pure titanium (grades 1-4) while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in ...
The properties of steel depend on its microstructure: the arrangement of different phases, some harder, some with greater ductility. At the atomic level, the four phases of auto steel include martensite (the hardest yet most brittle), bainite (less hard), ferrite (more ductile), and austenite (the most ductile). The phases are arranged by ...
Physically, these metals are soft (or brittle), have poor mechanical strength, and usually have melting points lower than those of the transition metals. Being close to the metal-nonmetal border , their crystalline structures tend to show covalent or directional bonding effects, having generally greater complexity or fewer nearest neighbours ...
Most definitions of the term 'refractory metals' list the extraordinarily high melting point as a key requirement for inclusion. By one definition, a melting point above 4,000 °F (2,200 °C) is necessary to qualify, which includes iridium, osmium, niobium, molybdenum, tantalum, tungsten, rhenium, rhodium, ruthenium and hafnium. [2]
The least brittle structural ceramics are silicon carbide (mainly by virtue of its high strength) and transformation-toughened zirconia. A different philosophy is used in composite materials, where brittle glass fibers, for example, are embedded in a ductile matrix such as polyester resin. When strained, cracks are formed at the glass–matrix ...
Osmium(II) iodide is a black solid [35] produced by the reaction of osmium tetroxide and hydroiodic acid at 250 °C in nitrogen: [34] OsO 4 + HI → OsI 2 + H 2 O. This compound decomposes in contact with water. [35] Osmium(III) iodide is a black solid that is produced by heating hexaiodoosmic acid (H 2 OsI 6). [34] This compound is insoluble ...