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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. As a result, carbide ...
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 ...
In solid phases, precipitation occurs if the concentration of one solid is above the solubility limit in the host solid, due to e.g. rapid quenching or ion implantation, and the temperature is high enough that diffusion can lead to segregation into precipitates. Precipitation in solids is routinely used to synthesize nanoclusters. [12]
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 ...
Aluminium–scandium alloys (AlSc) are aluminum alloys that consist largely of aluminium (Al) and traces of scandium (Sc) as the main alloying elements.In principle, aluminium alloys strengthened with additions of scandium are very similar to traditional nickel-base superalloys in that both are strengthened by coherent, coarsening resistant precipitates with an ordered L1 2 structure.
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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.