Effect of La on the crystallization behaviour of amorphous Al94 - xNi6Lax (x = 4-7) alloys

Melt spun and annealed Al-alloys containing 6 at.% Ni and 4-7 at.% La were investigated by means of differential scanning calorimetry (DSC), X-ray diffractometry (XRD), small angle neutron scattering (SANS), transmission electron microscopy and hardness measurements. XRD studies revealed that all the ribbons were fully amorphous, whereas SANS indicated concentration fluctuations. DSC showed that the amorphous alloys undergo a two-stage crystallization process upon heating. The details of the crystallization pathway depend on the La concentration. Upon annealing, SANS measurements revealed two different distributions of particles which can be explained by a core shell structure or two different types of particles. Moreover, significant changes in hardness occur which are attributed to changes in microstructure.