 | This article needs additional citations for verification .(October 2023) |
An aluminide is a compound that has aluminium with other elements. [1] Since aluminium is near the nonmetals on the periodic table, it can bond with metals differently from other metals. The properties of an aluminide are between those of a metal alloy and those of an ionic compound.
See category for a list.
Aluminium is a chemical element; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals; about one-third that of steel. It has a great affinity towards oxygen, forming a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, nonmagnetic and ductile. It has one stable isotope: 27Al, which is highly abundant, making aluminium the twelfth-most common element in the universe. The radioactivity of 26Al is used in radiometric dating.
In chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen atom with two electrons. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.
An intermetallic is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties. They can be classified as stoichiometric or nonstoichiometic intermetallic compounds.
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms a hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are colourless crystals, but samples are often contaminated with iron(III) chloride, giving them a yellow colour.
Raney nickel, also called spongy nickel, is a fine-grained solid composed mostly of nickel derived from a nickel–aluminium alloy. Several grades are known, of which most are gray solids. Some are pyrophoric, but most are used as air-stable slurries. Raney nickel is used as a reagent and as a catalyst in organic chemistry. It was developed in 1926 by American engineer Murray Raney for the hydrogenation of vegetable oils. Raney is a registered trademark of W. R. Grace and Company. Other major producers are Evonik and Johnson Matthey.
A superalloy, or high-performance alloy, is an alloy with the ability to operate at a high fraction of its melting point. Key characteristics of a superalloy include mechanical strength, thermal creep deformation resistance, surface stability, and corrosion and oxidation resistance.
Magnesium aluminide is an intermetallic compound of magnesium and aluminium. Common phases (molecular structures) include the beta phase (Mg2Al3) and the gamma phase (Mg17Al12), which both have cubic crystal structures. Magnesium aluminides are important constituents of 5XXX aluminium alloys (aluminium-magnesium) and magnesium-aluminium alloys, determining many of their engineering properties. Due to the advantage of low density and being strong, magnesium aluminide is important for aircraft engines. MgAl has also been investigated for use as a reactant to produce metal hydrides in hydrogen storage technology. Like many intermetallics, MgAl compounds often have unusual stoichiometries with large and complex unit cells.
Titanium aluminide, commonly gamma titanium, is an intermetallic chemical compound. It is lightweight and resistant to oxidation and heat, but has low ductility. The density of γ-TiAl is about 4.0 g/cm3. It finds use in several applications including aircraft, jet engines, sporting equipment and automobiles. The development of TiAl based alloys began circa 1970. The alloys have been used in these applications only since about 2000.
Aluminium fluoride is an inorganic compound with the formula AlF3. It forms hydrates AlF3·xH2O. Anhydrous AlF3 and its hydrates are all colorless solids. Anhydrous AlF3 is used in the production of aluminium metal. Several occur as minerals.
Sodium hexafluoroaluminate is an inorganic compound with formula Na3AlF6. This white solid, discovered in 1799 by Peder Christian Abildgaard (1740–1801), occurs naturally as the mineral cryolite and is used extensively in the industrial production of aluminium metal. The compound is the sodium (Na+) salt of the hexafluoroaluminate (AlF63−) ion.
Nickel aluminide typically refers to one of the two most widely used compounds, Ni3Al or NiAl, but can refer to most aluminides from the Ni-Al system. These alloys are widely used due to their corrosion resistance, low density and ease of production. Ni3Al is of specific interest as the strengthening γ' phase precipitate in nickel-based superalloys allowing for high temperature strength up to 0.7-0.8 of its melting temperature. Meanwhile, NiAl displays excellent properties such as low density (lower than that of Ni3Al), good thermal conductivity, oxidation resistance and high melting temperature. These properties make it ideal for special high temperature applications like coatings on blades in gas turbines and jet engines. However, both these alloys do have the disadvantage of being quite brittle at room temperature, with Ni3Al remaining brittle at high temperatures as well. However, it has been shown that Ni3Al can be made ductile when manufactured in single-crystal form rather than in polycrystalline form.
A gold–aluminium intermetallic is an intermetallic compound of gold and aluminium that occurs at contacts between the two metals.
Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name the compound has the formula Al2(C2H5)6 (abbreviated as Al2Et6 or TEA). This colorless liquid is pyrophoric. It is an industrially important compound, closely related to trimethylaluminium.
Cupalite is a rare mineral which is mostly composed of copper and aluminium, but might contain up to several percent of zinc or iron; its chemical structure is therefore described by an approximate formula (Cu,Zn)Al or (Cu,Fe)Al. It was discovered in 1985 in placers derived from serpentine, in association with another rare mineral khatyrkite (CuAl2). Both minerals are thus far restricted to the area of the Iomrautvaam, in the Khatyrka ultramafic (silicon-poor) zone of the Koryak–Kamchatka fold area, Koryak Mountains, Anadyrsky District, Chukotka Autonomous Okrug, Far Eastern Federal District, Russia. The mineral name derives from cuprum (Latin for copper) and aluminium. Its holotype (defining sample) is preserved in the Mining Museum in Saint Petersburg, and parts of it can be found in other museums, such as Museo di Storia Naturale di Firenze.
Aluminium borohydride, also known as aluminium tetrahydroborate, is the chemical compound with the formula Al(BH4)3. It is a volatile pyrophoric liquid which is used as a reducing agent in laboratories. Unlike most other metal–borohydrides, which are ionic structures, aluminium borohydride is a covalent compound.
Reactive multi-layer foils are a class of reactive materials, sometimes referred to as a pyrotechnic initiator of two mutually reactive metals, sputtered to form thin layers that create a laminated foil. On initiation by a heat pulse, delivered by a bridge wire, a laser pulse, an electric spark, a flame, or by other means, the metals undergo self-sustaining exothermic reaction, producing an intermetallic compound. The reaction occurs in solid and liquid phase only, without releasing any gas.
Aluminium triacetate, formally named aluminium acetate, is a chemical compound with composition Al(CH
3CO
2)
3. Under standard conditions it appears as a white, water-soluble solid that decomposes on heating at around 200 °C. The triacetate hydrolyses to a mixture of basic hydroxide / acetate salts, and multiple species co-exist in chemical equilibrium, particularly in aqueous solutions of the acetate ion; the name aluminium acetate is commonly used for this mixed system.
In chemistry, aluminium(I) refers to monovalent aluminium (+1 oxidation state) in both ionic and covalent bonds. Along with aluminium(II), it is an extremely unstable form of aluminium.
Iron aluminides are intermetallic compounds of iron and aluminium - they typically contain ~18% Al or more.
Aluminium (or aluminum) combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and aluminium compounds tend towards covalency; this behaviour is similar to that of beryllium (Be2+), an example of a diagonal relationship. However, unlike all other post-transition metals, the underlying core under aluminium's valence shell is that of the preceding noble gas, whereas for gallium and indium it is that of the preceding noble gas plus a filled d-subshell, and for thallium and nihonium it is that of the preceding noble gas plus filled d- and f-subshells. Hence, aluminium does not suffer the effects of incomplete shielding of valence electrons by inner electrons from the nucleus that its heavier congeners do. Aluminium's electropositive behavior, high affinity for oxygen, and highly negative standard electrode potential are all more similar to those of scandium, yttrium, lanthanum, and actinium, which have ds2 configurations of three valence electrons outside a noble gas core: aluminium is the most electropositive metal in its group. Aluminium also bears minor similarities to the metalloid boron in the same group; AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class.
 | This inorganic compound–related article is a stub. You can help Wikipedia by expanding it. |