Influence of La on the crystallisation behaviour of amorphous ( –7) alloys

Melt spun and subsequently annealed Al-alloys with 6 at.% Ni and 4–7 at.% La were investigated by differential scanning calorimetry, X-ray diffractometry (XRD). XRD reveals that the ribbons are fully amorphous in the as melt spun state. DSC shows that crystallisation proceeds in two stages which are sensitively influenced by the La content. The first stage compromises the formation of either fcc-Al (at low La content) or a bcc phase (at high La concentration) of yet unknown composition. Micro hardness changes significantly during annealing and can be correlated to the different stages of microstructural transformation as observed by XRD.