Msc. Shaymaa Mahmood
Introduction to Eng. Materials :
Since the earliest days of the evolution of mankind , the main distinguishing features between human begins and other mammals has been the ability to use and develop materials to satisfy our human requirements. Nowadays we use many types of materials, fashioned in many different ways, to satisfy our requirements for housing, heating, furniture, clothes, transportation, entertainment, medical care, defense and all the other trappings of a modern, civilised society. Most materials doesn't exist in its pure shape , it is always exist as a ores . During the present century the scope of metallurgical science has expanded enormously , so that the subject can now be studied under the following headings : a) Physical metallurgy b) Extraction metallurgy c) Process metallurgy In the recent years studying the metallurgy science gave to humanity an ever growing range of useful alloys. Whilst many of these alloys are put to purposes of destruction, we must not forget that others have contributed to the material progress of mankind and to his domestic comfort. This understanding of the materials resources and nature enable the engineers to select the most appropriate materials and to use them with greatest efficiency in minimum quantities whilst causing minimum pollution in their extraction, refinement and manufacture.
Selection of materials :
Let’s now start by looking at the basic requirements for selecting materials that are suitable for a particular application. For example figure 1 shows a connecter joining electric cables. The plastic casing has been partly cut away to show the metal connector. Plastic is used for the outer casing because it is a good electrical insulator and prevents electric shock if a person touches it. It also prevents the conductors touching each other and causing a short circuit. As well as being a good insulator the plastic is cheap, tough, and easily moulded to