Lecture 17 – Aluminium and its alloys Prescribed Text: Ref 1: Higgins RA & Bolton, 2010. Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. ISBN: 9781856177696 Readings: Callister: Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Edition, Wiley, New York. ISBN 9780470419977 Ashby 1: Ashby, M. & Jones, D., 2011, Engineering Materials 1: An Introduction to Properties, Applications and Design, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN: 9780080966656 Ashby 2: Ashby, M. & Jones, D., 2011, Engineering Materials 2: An Introduction to Microstructures and Processing, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN: 9780080966687   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

Aluminium and its alloys Reference Text Section Higgins RA & Bolton, 2010. Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann Ch 17 Additional Readings Section Engineering Materials and Processes

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

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

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 Engineering Materials and Processes

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

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) http://en.wikipedia.org/wiki/File:AluminumSlab.JPG Engineering Materials and Processes

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 669.722/RUSS Engineering Materials and Processes

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 Engineering Materials and Processes

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

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 Engineering Materials and Processes

Some common aluminium alloys http://www.globalmetals.com.au Engineering Materials and Processes

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

Engineering Materials and Processes Higgins Engineering Materials and Processes

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

Engineering Materials and Processes Higgins Engineering Materials and Processes

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

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

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

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

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

Wrought alloys which are heat-treated (Higgins 17.7) CAREFULLY READ 17.7.1 Heat-treatment Age Hardening Engineering Materials and Processes

Engineering Materials and Processes

Engineering Materials and Processes

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

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

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 http://www.youtube.com/watch?v=1GFst2IQBEM Engineering Materials and Processes 28

Define all the glossary terms. 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. http://www.youtube.com/watch?v=1GFst2IQBEM Engineering Materials and Processes 29