Effect of oxide particles on the crystallisation behaviour of Zr55Al10Ni5Cu30 alloy

In this work the easy-glass-forming amorphous alloy Zr55Al10Ni5Cu30 was obtained by the melt-spinning technique in the shape of ribbons. Two kinds of ribbons were produced, one with the pure alloy and another one with 1 wt.% of lanthanum oxide particles introduced in the molten alloy. Both ribbons were fully amorphous, according to X-ray diffraction; the inoculated amorphous ribbon was also analysed by scanning electron microscopy. Samples were cut from these amorphous ribbons and crystallised in a differential scanning calorimeter. No changes was observed in the glass transition temperature (Tg) or in the crystallisation on set temperature (Tx), and thus in the glass forming ability. The crystallisation products were analysed by X-ray diffraction and transmission electron microscopy. The pure alloy ribbon showed the presence of CuZr2 and Al3Zr4 stable phases plus a metastable phase. The inoculated crystallised ribbon on the other hand showed mainly the presence of the metastable phase plus a quasicrystalline phase which was not observed in the crystallised pure alloy. Thus the presence of lanthanum oxide drastically changed the phase selection for crystallisation.