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The technique of mechanical milling or grinding is widely used in the mineral, pharmaceutical, and ceramic industries. Small grinding machines are popular tools in scientific laboratories for preparing fine powders for various analyses and applications. Many people regard it as a simple, traditional technique. However, this book describes a very different ball milling technique: mechanical alloying. Mechanical alloying is actually a high-energy ball milling process for producing new nanostructured and metastable materials. In this process mechanical energy, rather than thermal, chemical, electric, or other common forms of energy, is used to create phase transformations and chemical reactions at very low temperatures. A large range of new materials, which are normally impossible or difficult to synthesize by other methods, have been produced by mechanical alloying. Therefore, mechanical alloying or highenergy ball milling is fundamentally different from conventional ball milling.Conventional ball milling offers a relatively low mechanical energy that sufficiently fractures large particles but does not change their crystalline structure. In contrast, high-energy ball milling has an impact energy typically 1000 times higher, and creates severe phase transformations and chemical reactions even at environmental temperature. The process of particle fracturing and size reduction in conventional ball milling is only the first stage of high-energy ball milling; a longer milling time is thus required for highenergy ball milling. Therefore, this book is not just about the ball milling technique, it also describes new metastable and nanostructured materials and related new synthesis processes.

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