Materials Science and Engineering A 449–451 (2007) 1049–1051 Influence of La on the crystallisation behaviour of amorphous Al 94-x Ni 6 La x (x = 4–7) alloys M. Wollgarten a, ∗ , K.L. Sahoo b , J. Haug a , J. Banhart a a Hahn-Meitner Institute, Materials Department SF 3, Glienicker Str. 100, D-14109 Berlin, Germany b National Metallurgical Laboratory, Jamshedpur 831007, India Received 21 August 2005; received in revised form 4 January 2006; accepted 28 February 2006 Abstract 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. © 2006 Published by Elsevier B.V. Keywords: Amorphous Al-alloys; Crystallisation; Scattering methods 1. Introduction Amorphous and nanocrystalline Al–TM–RE alloys (TM = transition metal, RE = rare-earth elements or Y), particularly in Al–Ni–RE alloys show promising mechanical properties which are superior to that of normal crystalline high-strength Al-alloys [1,2]. Various Al–TM–RE alloys are well investigated with re- gard to formation and stability of the amorphous phase and crys- tallisation pathways upon annealing (see e.g. [1,3–5]). Insuffi- cient knowledge exists for Al–TM–La system. Here, we report on the crystallisation pathways and the evolution of hardness of amorphous Al–Ni–La alloys. Besides the experiments reported here, Al 94-x Ni 6 La x alloys have been studied by small angle neutron scattering [6]. Those measurements support the view that the La content has signif- icant influence both on the initial microstructure (see hardness and crystallisation onset) and crystallisation pathways. 2. Experimental methods Ribbons of compositions Al 94-x Ni 6 La x (x = 4–7, desig- nated La4 to La7) were prepared by melt spinning at a wheel ∗ Corresponding author. E-mail address: wollgarten@hmi.de (M. Wollgarten). speed of 40 m/s. Further details of the preparation process can be found in Ref. [6]. The ribbons were found to be fully amorphous in X-ray diffraction (XRD) measurements and were further stud- ied by differential scanning calorimetry (DSC) under argon at- mosphere. Isochronal studies were done at heating rates ranging from 5 to 40 K/min. A second scan at the same rate was used for obtaining the base line. Isothermal experiments were conducted by heating the ribbons to the desired temperature at 100 K/min followed by a dwell period of up to 20 min and rapid cooling to room temperature. The annealed samples were studied by XRD, too. Energy filtered transmission electron microscopy (EFTEM) was used to study the La distribution in annealed samples. Evolution of hardness with temperature was studied by an- nealing as melt spun ribbons for 10 min at various temperatures between room temperature and 480 ◦ C followed by a Vickers- type hardness measurement. Determination of the full width at half maximum of the Al 〈111〉, Al 3 Ni 〈111〉 and Al 11 La 3 〈103〉 XRD maxima was used to estimate the mean particle sizes [7]. 3. Results and discussion The as melt spun material was found to be amorphous in XRD. Upon continuous heating in DSC each alloy shows two distinct crystallisation events. The peak temperatures (T P 1 ) of 0921-5093/$ – see front matter © 2006 Published by Elsevier B.V. doi:10.1016/j.msea.2006.02.351