Introduction

The mechanical properties of engineering materials depend strongly upon microstructure; it is therefore important that engineers should possess a basic understanding of how the microstructure is formed, and how this structure influences the engineering properties. The purpose of this practical period is to develop an understanding of the phase transformations which occur under conditions of slow cooling; under such conditions equilibrium is approached, and the phase diagram can be used as an aid to interpretation of the microstructure.

During this practical period you will use this Web site that introduces phase diagrams and explains their use. The site also introduces the phase diagrams of some real engineering alloys and you will study the microstructures of several selected alloys:

• Al-Cu alloys containing up to 40 wt%Cu
• Al-Si alloys with and without sodium 'modification'
• Steels

How to use this Web site

We have developed this Web site in order to help you understand phase diagrams and the use of the lever-rule calculation. There are some self-test questions at the end of most sections which you can use to check your understanding - but no record is kept of your scores.

Look through the site at your own speed, and remember that you can access it again at any time (for example when revising for exams). The Al-Cu, Al-Si and Steels sections contain some micrographs of real alloys and you are asked to sketch and label these at various points in the practical book.

Start looking through the site with the book to guide you - it summarises most of the main points of the package and can act as your "hard-copy" of the site. The tutors will be checking that you fill in the book during the session and you should discuss problems with them as they come round.

Note that details of Experiment 2 can be found in the Part I Materials book, starting on page 15.