Effect of oxide particles on the crystallisation behaviour of Zr55Al10Ni5Cu30 alloy

In this work the easy-glass-forming amorphous alloy Zr55Al10Ni5Cu30 was obt ained 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 w ere fully amorphous, according to X-ray diffraction; the inoculated amorpho us ribbon was also analysed by scanning electron microscopy. Samples were c ut from these amorphous ribbons and crystallised in a differential scanning calorimeter. No changes was observed in the glass transition temperature ( T-g) or in the crystallisation on set temperature (T-x), and thus in the gl ass forming ability. The crystallisation products were analysed by X-ray di ffraction and transmission electron microscopy. The pure alloy ribbon showe d the presence of CnZr(2) and Al3Zr4 stable phases plus a metastable phase. The inoculated crystallised ribbon on the other hand showed mainly the pre sence of the metastable phase plus a quasicrystalline phase which was not o bserved in the crystallised purl alloy. Thus the presence of lanthanum oxid e drastically changed the phase selection for crystallisation. (C) 2001 Els evier Science B.V. All rights reserved.