The evolution of the microstructure in amorphous Al_(85)Ce_8Ni_5Co_2 alloy during heat treatment and severe plastic deformation: A comparative study

摘要

The effect of three different devitrification routes, i.e. isothermal heat treatment, high pressure torsion and ball milling of amorphous Al_(85)Ce_8Ni_5Co_2 alloy have been studied systematically. The phase selection during the different crystallization sequences is explained by different thermodynamic barriers and growth rates. Low temperature heat treatment results in the formation of á-Al and a metastable phase (?). Although, the nucleation of Al_(11)Ce_3 phase is also likely in this temperature range, the lack of its growth is explained by kinetic considerations. Ball milling results in the formation of the stable phase mixture (á-Al and Al_(11)Ce_3). This process can be considered as a high temperature heat treatment at intermediate pressures (<2 GPa). High pressure torsion at the applied pressure of 6 GPa results in the primary formation of a-Al nanocrystals.