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- Mechanical_alloying abstract "Mechanical alloying (MA) is a solid-state powder processing technique involving repeated cold welding, fracturing, and re-welding of blended powder particles in a high-energy ball mill to produce a homogeneous material. Some other terms are also used in the literature on Mechanical Alloying. These include reaction (or reactive ball) milling, cryomilling, rod milling, mechanically activated annealing (M2A), double mechanical alloying (dMA), and mechanically activated self-propagating high-temperature synthesis (MASHS). Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from blended elemental or pre-alloyed powders. The non-equilibrium phases synthesized include supersaturated solid solutions, metastable crystalline and quasicrystalline phases, nanostructures, and amorphous alloys. This technique was expected to combine the high-temperature strength of oxide dispersion and the intermediate-temperature strength of gamma-prime precipitate. The required corrosion and oxidation resistance was also included in the alloy by suitable alloying additions. One consideration that should be avoided is powder contamination.Mechanical alloying is akin to metal powder processing, where metals may be mixed to produce superalloys. Mechanical alloying occurs in three steps. First, the alloy materials are combined in a ball mill and ground to a fine powder. A hot isostatic pressing (HIP) process is then applied to simultaneously compress and sinter the powder. A final heat treatment stage helps remove existing internal stresses produced during any cold compaction which may have been used. This produces an alloy suitable for high heat turbine blades and aerospace components.Design parameters include type of mill, milling container, milling speed, milling time, type, size, and size distribution of the grinding medium, ball-to-powder weight ratio, extent of filling the vial, milling atmosphere, process control agent, temperature of milling, and the reactivity of the species.The process of mechanical alloying involves the production of a composite powder particles by: Using a high energy mill to favor plastic deformation required for cold welding and reduce the process times Using a mixture of elemental and master alloy powders (the latter to reduce the activity of the element, since it is known that the activity in an alloy or a compound could be orders of magnitude less than in a pure metal) Eliminating the use of surface-active agents which would produce fine pyrophoric powder as well as contaminate the powder Relying on a constant interplay between welding and fracturing to yield a powder with a refined internal structure, typical of very fine powders normally produced, but having an overall particle size which was relatively coarse, and therefore stable.During high-energy milling the powder particles are repeatedly flattened, cold welded, fractured and rewelded. Whenever two steel balls collide, some amount of powder is trapped in between them. Typically, around 1000 particles with an aggregate weight of about 0.2 mg are trapped during each collision. The force of the impact plastically deforms the powder particles leading to work hardening and fracture. The new surfaces created enable the particles to weld together and this leads to an increase in particle size. Since in the early stages of milling, the particles are soft (if we are using either ductile-ductile or ductile-brittle material combination), their tendency to weld together and form large particles is high. A broad range of particle sizes develops, with some as large as three times bigger than the starting particles. The composite particles at this stage have a characteristic layered structure consisting of various combinations of the starting constituents. With continued deformation, the particles get work hardened and fracture by a fatigue failure mechanism and/or by the fragmentation of fragile flakes.".
- Mechanical_alloying thumbnail MA_Scheme.jpg?width=300.
- Mechanical_alloying wikiPageExternalLink MA.html.
- Mechanical_alloying wikiPageID "22051259".
- Mechanical_alloying wikiPageLength "5217".
- Mechanical_alloying wikiPageOutDegree "13".
- Mechanical_alloying wikiPageRevisionID "708261658".
- Mechanical_alloying wikiPageWikiLink Aerospace.
- Mechanical_alloying wikiPageWikiLink Ball_mill.
- Mechanical_alloying wikiPageWikiLink Category:Metallurgical_processes.
- Mechanical_alloying wikiPageWikiLink Cold_welding.
- Mechanical_alloying wikiPageWikiLink Hot_isostatic_pressing.
- Mechanical_alloying wikiPageWikiLink Oxide_dispersion-strengthened_alloy.
- Mechanical_alloying wikiPageWikiLink Powder_metallurgy.
- Mechanical_alloying wikiPageWikiLink Superalloy.
- Mechanical_alloying wikiPageWikiLink Turbine_blade.
- Mechanical_alloying wikiPageWikiLink File:MA_Scheme.jpg.
- Mechanical_alloying wikiPageWikiLink File:MA_Size_Distribution.jpg.
- Mechanical_alloying wikiPageWikiLinkText "Mechanical alloying".
- Mechanical_alloying wikiPageWikiLinkText "mechanical alloying".
- Mechanical_alloying wikiPageWikiLinkText "mechanical milling".
- Mechanical_alloying wikiPageUsesTemplate Template:Reflist.
- Mechanical_alloying subject Category:Metallurgical_processes.
- Mechanical_alloying hypernym Technique.
- Mechanical_alloying type TopicalConcept.
- Mechanical_alloying type Process.
- Mechanical_alloying comment "Mechanical alloying (MA) is a solid-state powder processing technique involving repeated cold welding, fracturing, and re-welding of blended powder particles in a high-energy ball mill to produce a homogeneous material. Some other terms are also used in the literature on Mechanical Alloying.".
- Mechanical_alloying label "Mechanical alloying".
- Mechanical_alloying sameAs Q5239697.
- Mechanical_alloying sameAs آلیاژسازی_مکانیکی.
- Mechanical_alloying sameAs Synteza_mechaniczna.
- Mechanical_alloying sameAs m.05p4dbr.
- Mechanical_alloying sameAs Механічне_легування.
- Mechanical_alloying sameAs Q5239697.
- Mechanical_alloying wasDerivedFrom Mechanical_alloying?oldid=708261658.
- Mechanical_alloying depiction MA_Scheme.jpg.
- Mechanical_alloying isPrimaryTopicOf Mechanical_alloying.