Evaluation of the volume fraction of nanocrystals devitrified in Al-based amorphous alloys

An evaluation of fcc-Al volume fractions (Vf) in Al90Ni5Nd5 and Al85Ni5Y6Co2Fe2 nanostructured composites has been made by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. For the Al90Ni5Nd5 alloy, there exhibited lower Vf values obtained by DSC than that by XRD due to increased interface energy and the overlapping of primary crystallization and structural relaxation features during nanocrystallization process. For the Al85Ni5Y6Co2Fe2 alloy, the Vf values calculated by both methods showed good agreements at low crystallinities, but apparent differences are observed at high crystallinities. This is due to compositional variations in the remaining amorphous matrix during devitrification.