Applications

From the previous chapters it becomes amply clear that the technique of mechanical alloying (MA) has been used extensively in synthesizing a variety of materials including stable and metastable phases. The types of material include nanocrystalline, crystalline, quasi-crystalline, and amorphous alloys. The incentive and the most important reason for the invention and development of the MA process was the production of oxide dispersion strengthened (ODS) materials in which fine particles of Y2O3 or ThO2 were uniformly dispersed in nickel-or iron-based superalloys. In the mid-1980s it was realized that MA was also capable of producing true alloys from elements that are not easily formed by conventional means or sometimes are even impossible to prepare, e.g., elements that are immiscible under equilibrium conditions. Investigations have revealed that metastable phases such as supersaturated solid solutions, nonequilibrium crystalline or quasi-crystalline intermediate phases, and amorphous alloys can be synthesized by MA. In addition, nanostructures with a grain size of a few nanometers, typically less than 100 nm, were also produced by MA. These metastable phases have interesting combinations of physical, chemical, mechanical, and magnetic properties and are being widely explored for potential applications [1-11]. It will be impossible to go into full details of each and every one of these developments, and so only a brief survey of the present and potential applications of the mechanically alloyed/milled materials is presented here. The two production facilities of Inco Alloys International in the United States have a combined annual capacity approaching 300,000 kg. The yield of the final product varies greatly with the product form and size, but the final wrought capacity is greater than 200,000 kg.