1. Lecture 17 – Aluminium and its alloys
Prescribed Text:
Ref 1: Higgins RA & Bolton, Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. ISBN:
Readings:
Callister: Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Edition, Wiley, New York. ISBN
Ashby 1: Ashby, M. & Jones, D., 2011, Engineering Materials 1: An Introduction to Properties, Applications and Design, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Ashby 2: Ashby, M. & Jones, D., 2011, Engineering Materials 2: An Introduction to Microstructures and Processing, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Lecture (2 hrs):
Ref 1, Ch 1: Engineering materials;
Ref 1 Ch 2: Properties of materials.
Laboratory 1 (2 hrs): Hardness test
Callister: Ch 1, 2, 18-21
Ashby 1: Ch 1, 2
Ashby 2: Ch 1 1

2. Aluminium and its alloys
Reference Text
Section
Higgins RA & Bolton, Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann
Ch 17
Additional Readings
Section
Engineering Materials and Processes

3. Aluminium and its alloys
Note: This lecture closely follows text (Higgins Ch17)
Engineering Materials and Processes

4. Aluminium (Higgins 17.1) READ HIGGINS 17.1
Aluminium is very reactive – strongly electropositive and readily combines with all the non-metal (electronegative) ions.
So it wasn’t produced until 1825 (Oersted) when it was more expensive than gold.
Not any more!
Aluminium
Wikipedia
Engineering Materials and Processes

5. Uses of aluminium READ HIGGINS 17.1
Demand for Aluminium was driven by aircraft.
Today it is widely spread though most industries.
Lightweight
Durable
Easy to form, extrude, diecast
Good finishes
High strength to weight
Engineering Materials and Processes

6. Worldwide Aluminium Production
Aluminium needs electricity. It is actually easier to ship the ore to the electrical energy source rather than bring the electricity to the ore.
Engineering Materials and Processes

7. The extraction of aluminium (Higgins 17.2)
READ HIGGINS 17.2
The modern electrolytic process turns bauxite (Al2O3) into aluminium metal. Unlike a blast furnace that removes oxygen (reduction) with coke, aluminium requires electricity to do this:
All 91 megaJoules of the stuff per kg!
So aluminium product suits countries
with ample hydroelectricity.
(e.g. Norway)
Engineering Materials and Processes

8. The extraction of aluminium (VIDEO)
The making of aluminium [videorecording] Advanced version. Russell, Geoff.
1993. Video Education Australia. DVD (30 min.)
Explains the process of smelting aluminium using the smelter at Portland smelter in Victoria as an example.
Detailed analysis of refining and smelting of aluminium. Covers production, economic, environmental issues. Excellent quality.
DVD  /RUSS
Engineering Materials and Processes

9. Properties of aluminium (Higgins 17.3)
READ HIGGINS 17.3
Conductivity (electrical and thermal)
Corrosion resistance
Ductility for forming, extrudion
Low MP for diecasting
Highly machinable
Lightweight
Good finishes - anodising
High strength to weight
Lots of alloys and heat treatments
Engineering Materials and Processes

10. Aluminium alloys (Higgins 17.4)
READ HIGGINS 17.4
4 main classes of aluminium alloys
Wrought
Cast
Non-heat Treatable
Heat Treatable
Traps to watch out for…
1. A common mistake is to call aluminium components “alloy” simply because it starts with “al”. Brass and even steel is “alloy”
2. In USA, Aluminium is called Aluminum. Same stuff, different name.
Engineering Materials and Processes

11. Aluminium alloys (Higgins 17.4)
READ HIGGINS 17.4
Wrought alloys
Cast alloys
READ HIGGINS 17.5
17.5 Wrought alloys which are not heat-treated
17.6 Cast alloys which are not heat-treated
Engineering Materials and Processes

12. Some common aluminium alloys
Engineering Materials and Processes

13. Aluminum alloys
They are normally identified by a four figure system which originated in the USA and is now universally accepted (with variations – usually extra digits).
Note:
Higgins is based on British Standards (BS) from which most Australian standards are based.
Where it is written
1473: 5083
It simply means
BS 1473 and grade 5083
(e.g. table 17.1)
Engineering Materials and Processes

14. Engineering Materials and Processes
Higgins
Engineering Materials and Processes

15. READ HIGGINS
Figure 17.2 The aluminium-silicon thermal equilibrium diagram. The effects of 'modification' on both the position of the eutectic point and the structure are also shown.
Higgins
Engineering Materials and Processes

16. Engineering Materials and Processes
Higgins
Engineering Materials and Processes

17. Engineering Materials and Processes
(i) 12 per cent silicon in aluminium - unmodified, as cast. Since this alloy contains more than the eutectic amount (11.6 per cent) of silicon (see Figure 17.2),
primary silicon (angular crystals) are present. The eutectic is coarse and brittle and consists of 'needles' of silicon in a matrix of a solid solution because the layers of a in the eutectic have fused together to form a continuous mass (the amount of silicon being only 11.6 per cent of the eutectic so that the layers of a would be roughly ten times the thickness of those in silicon),
Higgins
Engineering Materials and Processes

18. Engineering Materials and Processes
(ii) The same alloy as (i) but modified by the addition of 0.01 per cent sodium. This has the effect of displacing the eutectic point to 14 per cent silicon so that the structure now consists of primary crystals of a (light) in a background of extremely fine-grained eutectic (dark). The alloy is now stronger and tougher,
Higgins
Engineering Materials and Processes

19. Engineering Materials and Processes
(iii) A duralumin- type alloy in the 'as extruded' condition (unetched). The particles consist mainly of CuAl2 (see Figure 17.4) elongated in the direction of extrusion.
Most of this CuAl2 would be absorbed during subsequent solution treatment.
Higgins
Engineering Materials and Processes

20. Wrought alloys which are heat-treated (Higgins 17.7)
Figure 17.4 Structural changes which take place during the heat-treatment of a duralumin-type of alloy.
Higgins
Engineering Materials and Processes

21. Wrought alloys which are heat-treated (Higgins 17.7)
Figure 17.5 The effects of time and temperature of precipitation treatment
on the strength of duralumin.
Higgins
Engineering Materials and Processes

22. Wrought alloys which are heat-treated (Higgins 17.7)
CAREFULLY READ
Heat-treatment
Age Hardening
Engineering Materials and Processes

23. Engineering Materials and Processes

24. Engineering Materials and Processes

25. Cast alloys which are heat-treated (Higgins 17.8)
Engineering Materials and Processes

27. Online Resources. Aluminium Non Ferrous Metals
h ttp://
S how this website on screen. Will be using this later.
Engineering Materials and Processes 27

28. GLOSSARY
Bauxite
Electrolysis
Precipitation hardening
Age hardening
Wrought
Cast
Anodising
Oxide layer
As quenched
Alumina
Glossary
Engineering Materials and Processes 28

29. Define all the glossary terms.
QUESTIONS
Moodle XML: Some questions in Non-Ferrous
Define all the glossary terms.
Aluminium has been dubbed solid electricity. Producing 1 kg of Aluminium uses 91 MJ. Calculate the cost to produce 1 kg of aluminium based on current domestic electricity charges. What rate would you expect a smelter to pay?
It has been stated that aluminium is the most economically viable material for recycling. Comment on this statement using a comparison of current recycling values for other common scrap materials like metals, plastics and paper products. Ref: List the proportions of Aluminium that are lost during recycling.
Why have car radiators switched from copper to aluminium? Explain why these two metals dominate other areas like evaporators and condensers in air conditioning and heat exchangers for heat reclamation systems for reducing energy losses in manufacturing and process plants.
Explain the age hardening process and mechanism for an aluminium alloy such as Duralumin.
Explain why Aluminium is highly reactive yet is used for its corrosion resistance.
Engineering Materials and Processes 29