Cryomilling involves the ball milling of metal powders in a liquid nitrogen medium. It has been used to produce bulk nanocrystalline materials with high thermal stability [1]. The benefits of milling at cryogenic temperatures include accelerated grain refinement, reduced oxygen contamination from the atmosphere, and minimized heat generated during milling. This mechanical attrition process induces severe repetitive deformation in powders. During milling, the powder particles are repeatedly sheared, fractured and cold-welded, and severe plastic deformation effects the formation of nanostructures [2]. Cryomilled powders exhibit typical grain sizes of 20–60 nm [3].