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Gamma double prime (γ"): This phase typically is Ni 3 Nb or Ni 3 V and is used to strengthen Ni-based superalloys at lower temperatures (<650 °C) relative to γ'. The crystal structure of γ" is body-centered tetragonal (BCT), and the phase precipitates as 60 nm by 10 nm discs with the (001) planes in γ" parallel to the {001} family in γ.
In these alloys the volume fraction of the γ' precipitates is as high as 80%. [7] Because of this high volume fraction, the evolution of these γ' precipitates during the alloys' life cycles is important: a major concern is the coarsening of these γ' precipitates at high temperature (800 to 1000 °C), which greatly reduces the alloys ...
In age-hardening or precipitation-strengthening varieties, small amounts of niobium combine with nickel to form the intermetallic compound Ni 3 Nb or gamma double prime (γ″). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures. The formation of gamma-prime crystals increases over time ...
Precipitation hardening, also called age hardening or particle hardening, is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and some steels, stainless steels, and duplex stainless steel.
Precipitation in solids is routinely used to synthesize nanoclusters. [12] In metallurgy, precipitation from a solid solution is also a way to strengthen alloys. Precipitation of ceramic phases in metallic alloys such as zirconium hydrides in zircaloy cladding of nuclear fuel pins can also render metallic alloys brittle and lead to their ...
A Guinier–Preston zone, or GP-zone, is a fine-scale metallurgical phenomenon, involving early stage precipitation. [1] [2] GP-zones are associated with the phenomenon of age hardening, whereby room-temperature reactions continue to occur within a material through time, resulting in changing physical properties. In particular, this occurs in ...
Ostwald ripening is also the key process in the digestion and aging of precipitates, an important step in gravimetric analysis. The digested precipitate is generally purer, and easier to wash and filter. Ostwald ripening can also occur in emulsion systems, with molecules diffusing from small droplets to large ones through the continuous phase.
Nickel-based superalloys boast improved strength and creep resistance due to their composition and resultant microstructure. The gamma (γ) FCC nickel is alloyed with aluminum and titanium in order to precipitate a uniform dispersion of the coherent Ni 3 (Al,Ti) gamma-prime (γ') phases. The finely dispersed γ' precipitates impede dislocation ...