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Molybdenum carbide is an extremely hard, refractory, ceramic material, commercially used in tool bits for cutting tools. There are at least three reported phases of molybdenum carbide: γ-Mo C, β-Mo 2 C, and γ'. The γ phase is structurally identical to tungsten carbide. [1] β-Mo 2 C has been suggested as a catalyst for carbon dioxide ...
The solidus is the locus of temperatures (a curve on a phase diagram) below which a given substance is completely solid (crystallized). The solidus temperature specifies the temperature below which a material is completely solid, [ 2 ] and the minimum temperature at which a melt can co-exist with crystals in thermodynamic equilibrium .
The phase diagram shows, in pressure–temperature space, the lines of equilibrium or phase boundaries between the three phases of solid, liquid, and gas. The curves on the phase diagram show the points where the free energy (and other derived properties) becomes non-analytic: their derivatives with respect to the coordinates (temperature and ...
The name derived from Ancient Greek Μόλυβδος molybdos, meaning lead, since its ores were confused with lead ores. [12] Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele.
Lanthanides also form carbides (sesquicarbides, see below) with formula M 2 C 3. Metals from group 11 also tend to form acetylides, such as copper(I) acetylide and silver acetylide . Carbides of the actinide elements , which have stoichiometry MC 2 and M 2 C 3 , are also described as salt-like derivatives of C 2− 2 .
The fourth condition (straight solidus/liquidus segments) may be relaxed when numerical techniques are used, such as those used in CALPHAD software packages, though these calculations rely on calculated equilibrium phase diagrams. Calculated diagrams may include odd artifacts (i.e. retrograde solubility) that influence Scheil calculations.
In Greece, copper was known by the name chalkos (χαλκός). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as aes Cyprium, aes being the generic Latin term for copper alloys and Cyprium from Cyprus, where much copper was mined. The phrase was simplified to cuprum, hence the ...
In each of the three classes of Laves phase, if the two types of atoms were perfect spheres with a size ratio of /, [2] the structure would be topologically tetrahedrally close-packed. [3] At this size ratio, the structure has an overall packing volume density of 0.710. [ 4 ]