Critical grain size for nanocrystalline-to-amorphous phase transition in Al solid solution

This study reports experimental results and analysis of the amorphization reaction in an engineering Al alloy (Al > 94 wt%) during mechanical milling in a liquid nitrogen environment (cryomilling). We propose that the amorphization reaction occurred as a result of the magnitude of the strain field during cryomilling and the presence of a low temperature (e. g., 88 K). These two factors provided the driving force for the crystalline-to-amorphous transition and helped maintain the amorphous phase below the glass transition temperature.