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ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) Lecture 17 – Aluminium and its alloys. Aluminium and its alloys. EMMAT101A Engineering Materials and Processes. Aluminium and its alloys.

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Aluminium and its alloys

ENMAT101A Engineering Materials and ProcessesAssociate Degree of Applied Engineering (Renewable Energy Technologies)Lecture 17 – Aluminium and its alloys


Aluminium and its alloys

Aluminium and its alloys

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Aluminium and its alloys

Note: This lecture closely follows text (Higgins Ch17)

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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

http://www.alu-support.com/newsdisp.php?ID=129

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Worldwide Aluminium Production

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.

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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 megajoulesof the stuff per kg!

So aluminium product suits countries

with ample hydroelectricity.

(e.g. Norway)

http://en.wikipedia.org/wiki/File:AluminumSlab.JPG

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

The extraction of aluminium (VIDEO)

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 669.722/RUSS

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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

http://www.teknologiateollisuus.fi

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Aluminium alloys (Higgins 17.4)

READ HIGGINS 17.4

4 main classes of aluminium alloys

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.

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Aluminium alloys (Higgins 17.4)

READ HIGGINS 17.4

17.4.1 Wrought alloys

17.4.2 Cast alloys

READ HIGGINS 17.5

17.5 Wrought alloys which are not heat-treated

17.6 Cast alloys which are not heat-treated

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Some common aluminium alloys

http://www.globalmetals.com.au

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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)

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Higgins

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Higgins

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

(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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

(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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

(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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

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

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Wrought alloys which are heat-treated (Higgins 17.7)

CAREFULLY READ

17.7.1 Heat-treatment

Age Hardening

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Cast alloys which are heat-treated (Higgins 17.8)

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

Online Resources.

Aluminium

Non Ferrous Metals

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

GLOSSARY

  • Bauxite

  • Electrolysis

  • Precipitation hardening

  • Age hardening

  • Wrought

  • Cast

  • Anodising

  • Oxide layer

  • As quenched

  • Alumina

Glossary

http://www.amari-ireland.com/online-tools/glossary/aluminium/a

EMMAT101A Engineering Materials and Processes


Aluminium and its alloys

QUESTIONS

Moodle XML: Some questions in 10106 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: http://en.wikipedia.org/wiki/Aluminium. 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.

EMMAT101A Engineering Materials and Processes


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