The Influence of the Third Component in the Microstructure of the Rapid Solidified Al-Fe-X alloys

F. AUDEBERT; F. SAPORITI; B. ARCONDO

Foz do Iguazu

Workshop; Workshop on Metastable and Nanostructured Materials; 2003

Amorphous and nano-structured Al-based alloys have been studied intensively during the last decade because they have good mechanical properties and promising technological applications. Especially, in the Al-Fe-X systems is possible to obtain, by rapid solidification, different classes of microstructure by combining several kind of phases: amorphous, crystalline solid solutions, intermetallic compounds and quasicrystals. The kind of phases that can be formed is strongly controlled by the third component (X) of the alloy. During the rapid solidification, the nucleation process have greater influence than the growing process on the microstructure. Then, the influence of the third component on the phase selection during the rapid solidification can be studied by a structural characterisation of a group of the alloys using complementary techniques. In the present work, rapid solidified Al-Fe and Al-Fe-X alloys, with X= MM (Mischmetal: rare earth mixture), Nb, Sb, V or Ni, were studied. The alloys were produced my the Melt Spinning technique and the structural characterisation was carried out by means of X-ray diffraction, Mössbauer spectroscopy and complementary by transmission electron microscopy. The Al-Fe-Nb and the Al-Fe-MM alloys presented a fully amorphous structure, the Al-Fe-Sb and the Al-Fe-Ni showed a microstructure composed by crystalline phases and the Al-Fe-V sample resulted in a nanoquasicrystalline alloy composed by icosahedral particles embedded in an -Al matrix. The results suggest that Al-Fe icosahedral clusters are formed in the super-cooled liquid. The interaction of the third component on these clusters and its influence on the phase selection during the rapid solidification is discussed.