NANOCRYSTALLINE FORMATION OF ALNINDCU MATERIALS - A KINETIC-STUDY

The crystallization kinetics of amorphous Al87Ni7Nd3Cu3 is discussed. Experimental procedure includes the determination of the evolution of devitrification under isothermal and continuous heating conditions by means of differential scanning calorimetry. Primary crystallization of alpha-Al occurs followed by eutectic precipitation of alpha-Al + inte rmetallic phases, mainly Al3Ni, at higher temperatures. Eutectic cryst allization occurs with an apparent activation energy of 1.4 eV. The fo rm of the calorimetric peak is very asymmetric as a function of both t emperature (under continuous heating) and time (under isothermal annea ling). This strongly suggests that primary crystallization of alpha-Al is limited by diffusion. Eutectic crystallization of the remaining am orphous phase splits in two overlapped peaks. Their respective activat ion energy values are 1.9 and 2.1 eV.