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Co-based superalloys depend on carbide precipitation and solid solution strengthening for mechanical properties. While these strengthening mechanisms are inferior to gamma prime (γ') precipitation strengthening, [ 1 ] cobalt has a higher melting point than nickel and has superior hot corrosion resistance and thermal fatigue.
Directional solidification is the preferred technique for casting high temperature nickel-based superalloys that are used in turbine engines of aircraft. Some microstructural problems such as coarse dendritic structure, long dendrite side branches, and porosity hinder the full potential of single crystal ni-based alloys. [6]
In nickel-based superalloys, regions of Ni 3 Al (called γ' phase) precipitate out of the nickel-rich matrix (called γ phase) to give high strength and creep resistance. Many alloy formulations are available and they usually include other elements, such as chromium, molybdenum, and iron, in order to improve various properties.
Inconel 625 was designed as a solid solution strengthened material with no significant microstructure. This holds true at low and high temperatures, but there is a region (923 to 1148 K) where precipitates form that are detrimental to the creep properties, and thus the strength, of the alloy.
Inconel is a nickel-chromium-based superalloy often utilized in extreme environments where components are subjected to high temperature, pressure or mechanical loads. Inconel alloys are oxidation- and corrosion-resistant. When heated, Inconel forms a thick, stable, passivating oxide layer protecting the surface from further attack.
Nimonic alloys typically consist of more than 50% nickel and 20% chromium with additives such as titanium and aluminium. The main use is in gas turbine components and extremely high performance reciprocating internal combustion engines.
Many nickel-based superalloys depend on solid solution as a strengthening mechanism. The most popular example is the Inconel family, where many of these alloys contain chromium and iron and some other additions of cobalt, molybdenum, niobium, and titanium. [7]
Alloys of nickel are the most common but includes iron aluminum alloys. [1] Applications include high temperature turbine blades and heat exchanger tubing, [2] while steels are used in nuclear applications. [3] ODS materials are used on spacecraft to protect the vehicle, especially during re-entry. Noble metal ODS alloys, for example, platinum ...