8.1 Flashcards
1
Q
What is alloy?
A
An alloy is defined as a mixture of two or more elements with a certain composition in which the major component is a metal.
2
Q
What are the aims of alloying?
A
- To prevent corrosion of metals
- To improve the appearance of metals
- To turn a metal into a superconductor
- To increase the strength and hardness of metals
3
Q
Why are alloys harder than pure metals?
A
- same size
- orderly structure
- The empty spaces between the atoms
- When force is applied, the layers of atoms slide over each other easily
- The atoms are forced to fill in the empty spaces between them.
- Thus, pure metals can be knocked into different shapes (malleable) & can be stretched into thin wires without breaking (ductile).
In alloy,
- foreign atoms
- disrupting the regular or orderly arrangement of the metal atoms
- the layers of atoms are prevented from sliding over each other easily.
4
Q
Carbon steel (Steel)
A
98% - iron
- 2-2% - carbon
- hard and strong
- building structures (framework)
- body of vehicles
- spring
5
Q
Stainless steel
A
73% iron 18% chromium 8% nickel 1% carbon - does not rust, hard and shiny - surgical instruments and kitchenware
6
Q
Brass
A
70% copper
30% zinc
- harder than copper, shiny and does not corrode
- padlocks, musical instruments, electrical connectors
6
Q
Cupro-nickel
A
75% copper
25% nickel
- hard and shiny
- coins
7
Q
Bronze
A
90% copper
10% tin
- harder than copper and does not corrode
- ship propellers, statues and medals
8
Q
Magnalium
A
70% aluminium
30% magnesium
- light hard and strong
- aeroplane bodies
9
Q
Duralumin
A
93% aluminium 3% copper 3% magnesium 1% manganese - light hard and strong - high voltage electric cables, racing bike frames
10
Q
Solder
A
70% tin
30% lead
- low melting point
- joining wires and pipes
11
Q
Pewter
A
95% tin
- 5% antimony
- 5% copper
- does not rust, shiny
- decorative ornaments, souvenirs
