4.4.11 List two design criteria for
super alloys.
Oxidation is the interaction between oxygen and different
substances when they make contact, such as rust Fe2O3.
Oxidation resistance is the ability of a material to resist
the direct and indirect attack of oxygen (oxidation).
Creep is the tendency of a metal (or material) to slowly
move or deform permanently due to the long term
exposure of stress that are below the yield strength or
ultimate strength of the metal. Creep is more severe when
metals are subjected to near the melting point heat for
long periods of time.
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4.4.12 Identify applications for
super alloys.
Super alloys can be based on iron, cobalt or nickel.
Nickel-based super alloys are particularly resistant to
temperature and are appropriate materials for use in
aircraft engines and other applications that require
high performance at high temperatures, for example,
rocket engines, chemical plants.
Super alloys are used where there is a need for high
temperature strength and corrosion/oxidation
resistance.
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Other uses of super alloys are: aircraft and industrial
gas turbines, space vehicles, submarines, nuclear
reactors, military electric motors and heat exchanger
tubing.
The space shuttle uses a super alloy for its body and
main engine and other parts likely to be exposed to
high temperature such as combustion zones also.