Nonferrous Alloys Flashcards
Aluminum properties
Much lighter than steel (about one third as dense)
Much less stiff and less strong than steel (about a factor 3 lower stiffness, a factor of 4 lower strength). Specific strength and stiffness comparable to steel.
Slightly more expensive than steel
Very low melting temperature for a structural alloy
No endurance limit in fatigue
Much higher thermal and electrical conductivity than iron/steel
Better natural corrosion resistance because of the formation of Al2O3 passivating layer
Aluminum Applications
Lightweight structures (aerospace, sports equipment, …)
Outdoor applications were some corrosion resistance is desirable (ladders)
Moderate performance heat exchangers, heat sinks, and electrical conductors
Copper properties
Exceptionally high thermal and electrical conductivity (better than aluminum)
Good natural corrosion resistance because the element is relatively noble
Extremely ductile and machinable
Higher density than steel
More expensive than steel
Moderate melting temperature (lower than steel)
Copper applications
Pure copper: High performance heat exchangers, heat sinks, and electrical conductors
Brass (Cu + Zn): Used for connectors, bathroom fixtures
Bronze (Cu + Sn): High strength electrical conductors (e.g. electrical switch springs), bearings and bushings, statues
Magnesium properties
Extremely low density (lower than aluminum)
All mechanical/chemical/thermal properties somewhat worse than aluminum, but specific strength and stiffness are high because of very low density
Reactive: small particles can ignite
Magnesium applications
Where extreme light weight is most important property (tennis racket, race car engine)
Titanium properties
Lower density than steel, but strength comparable to steel, which results in exceptional specific strength
Very good natural corrosion resistance
Good high temperature strength and creep resistance
Biocompatible
Much more expensive than steel
Titanium applications
Lightweight applications where very high stresses are expected (fighter aircraft landing gear)
Implants, joint replacements
Superalloys (Iron/nickel, nickel, cobalt)
Properties
Nickel and cobalt have physical and mechanical properties similar to iron
They (in particular Nickel) have corrosion and oxidation resistance superior to iron
They have excellent high temperature strength and creep resistance
They are more expensive
Superalloys (Iron/nickel, nickel, cobalt)
Applications
Where excellent high temperature strength is required, but density must be kept low and the environment is aggressive
Refractory metals and alloys
properties
Exceptionally high melting temperature
Very high stiffness, strength, and creep resistance
Very high density (can be two or three times denser than steel)
Very vulnerable to oxidation
Refractory metals and alloys
applications
Where exceptional high temperature strength and creep resistance is required, but density is unimportant and a protective environment can be provided.
Precious metals
properties
Expensive
Usually noble elements (Corrosion resistant)
Excellent thermal and electrical conductivity
Precious metals applications
Money (Bullion, coin)
Jewelry
Platinum and palladium are used as catalysts for chemical reactions
Gold and palladium are used to coat electrical contacts to prevent environmental degredation of the contact
