On the minimum grain size produced by milling Zn–22%Al

Nanocrystalline (nc) Zn–22%Al, which consists of an FCC Al phase and an HCP Zn phase, has been synthesized by cryomilling. The results show that during cryomilling, the grain sizes of the Al and the Zn phases decreased with milling time, and that after 16 h of milling, they approached minimum values of 33 and 41 nm, respectively. While the minimum grain sizes of the Al and the Zn phases agree well with the trends of very recent correlations between the minimum gain size and materials parameters such as melting point and hardening, they are higher than those reported for Al (22–26 nm) and Zn (20 nm). Possible reasons for this discrepancy are discussed.