In this lesson, we are going to take a closer look at metal alloys. First, we will define what an alloy is and how dislocations strengthen alloys. The e-textbook breaks metal alloys into two classes of metal alloys: ferrous and nonferrous alloys. Ferrous is simply the Latin name for iron, so ferrous alloys are simply iron alloys (which means that it is mostly iron mixed with lesser amounts of other metals or nonmetals) and nonferrous alloys are non-iron alloys. In the reading for this lesson, you will see the composition, properties, and applications of a wide variety of metal alloys. The video for this lesson highlights the properties and applications of some of the metal alloys and puts the materials development of the highlighted metal alloys in historical context.