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

An evaluation of fcc-Al volume fractions (V(f)) in Al(90)Ni(5)Nd(5) and Al(85)Ni(5)Y(6)Co(2)Fe(2) nanostructured composites has been made by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. For the Al(90)Ni(5)Nd(5) alloy, there exhibited lower V(f) 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 Al(85)Ni(5)y(6)Co(2)Fe(2) alloy, the V(f) 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. (C) 2008 Elsevier B.V. All rights reserved.