L14: Non- Ferrous Metal And Alloys

Question 1

What are the properties of copper alloys?

Answer 1

Good electrical conductivity and corrosion resistance

Not suitable for heat treatment-strengthen by work hardening or solid solution strengthening

Question 2

Copper plus zinc is what?

Answer 2

Brass -elec fitting and furniture hardware

> 32wt%Zn a and b phases so brittle due to dispersion hardening

<32wt% Zn a phase only - ductile - can be cold worked to improve strength

Question 3

Copper with Sn forms what?

Answer 3

Bronze

Question 4

What are the properties of pure aluminium?

Answer 4

1/3 the density of steel
Ductile
High thermal and electrical conductivity 
Corrosion resistant 
Low mp

Question 5

What is Al often alloyed with and what property does this change?

Answer 5

Reduces corrosion resistance

Mg, Mn, Si, Cu, Zn

Question 6

What are cast alloys?

Answer 6

Alloys not suitable to form or shape- have to be cast

Question 7

What are wrought alloys?

Answer 7

Amenable to deformation

Question 8

What are Non- heat treatment alloys

Answer 8

Consists of a single phase - strengthened by solid solution strengthening or dispersion strengthening

Question 9

What are heat treatable alloys?

Answer 9

Can be age hardened- Mg2Si formed in Al matrix good formability,

Often by 2 of the alloying elements as intermetallic compounds

Question 10

What are some applications of Al alloys?

Answer 10

Aircraft parts, automotive parts, food containers, drink cans

Question 11

How does alloy designation work?

Answer 11

IADS COMMONLY USED
Wrought- 4 digits
Cast - 4 digits with decimal point

Both-
1st digit indicates main alloying element
Others indicate specific alloy
Letters and numbers after 4 digits specify heat treatment T-age hardened O-annealed H-cold worked

Question 12

What does porosity in a casting due to the strength of the structure?

Answer 12

Weakens it- stress raisers

Question 13

What are the properties of titanium alloys?

Answer 13

High corrosion resistance, strength to weight ratio, melting point

Easily alloyed for special applications eg aircraft, hip joints

Highly ductile, easily forged and machined

V chemically reactive at high temps - needs expensive refining, melting and casting

Question 14

What are the properties of Mg alloys?

Answer 14

Use Al, Zn, Mn
V light weight
Used in aircraft, missiles, power tools, computers, cars

Can be hazardous due to high reactivity with O2 - burns

Question 15

What are superalloys?

Answer 15

Ni, Fe-Ni, Co alloys with large quantities of other elements

High strength at high temp, creep and corrosion resistance

Question 16

What are refractory metals?

Answer 16

Niobium, molybdenum, tungsten, tantalum

Strong metallic bonding- v high melting points and Ym and high hardness even at high temp

Used for Light filaments, welding electrodes, extrusion dies