Sixty Years of Mechanical Alloying—Past Achievements, Current Challenges, and Future Prospects

Mechanical alloying (MA), a completely solid‐state high‐energy powder processing method, was initially used to develop Ni‐based and Fe‐based superalloys containing oxide dispersions for applications at high temperatures and requiring high strength. MA is currently an established materials process to synthesize a variety of nonequilibrium alloys with unique microstructures and properties. Supersaturated solid solutions, metastable intermediate phases, amorphous alloys, quasicrystalline alloys, nanostructures, and nanocomposites, and high‐entropy alloys are some of the materials developed using MA. These advanced structural and functional materials exhibit great potential with widespread applications. Several new and novel applications have also been recently developed. A major concern in using this technique to produce advanced materials is the inherent contamination experienced by the milled powder. In the present article, the past achievements during the last 60 years and current challenges are described in brief. Methods to decrease powder contamination and ways to reduce the cost of powders produced are also discussed. It is also shown that while the MA concept is straightforward, the outcome of the process can be stochastic, depending on many variables which must be experimentally determined since no comprehensive process model exists. The article concludes with the future prospects of this materials processing technique.