INTECIN   20395
INSTITUTO DE TECNOLOGIAS Y CIENCIAS DE LA INGENIERIA "HILARIO FERNANDEZ LONG"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Nb effect on Rapid Solidified Al-based Alloys
Autor/es:
F. AUDEBERT; M. GALANO; F. SAPORITI; P. QUINN
Lugar:
Moscu
Reunión:
Congreso; IXX International Symposium on Metastable, Amorphous and Nanostructured Materials; 2012
Resumen:
Rapid Solidification processes allow obtaining Al-based alloys with several types of microstructures which can combine amorphous, crystalline and quasicrystalline phases. Therefore, the combination of different kind of phases produce alloys that can have excellent combination of properties, like high strength and toughness with good corrosion behaviour. The microstructure of the rapid solidified (RS) alloys is mainly controlled by the nucleation process during the rapid solidification. Therefore, the chemical composition is a key factor that determines the microstructure and properties obtained in the RS alloys. The understanding of the effect of each solute element in the RS Al-based alloys can help to predict the microstructure to be obtained and its properties. The effect of Fe, Ni, Nb and Ce in the structure of the liquid of Al and in the RS alloys has been investigated. The study has been done combining experimental and modeling techniques, for instance using Mössbauer Spectroscopy (MS), XRD, EXAFS, TEM and Molecular Dynamic Simulation. The total structure factors and the reduced atomic distribution functions were used in the comparative analysis. Moreover, cluster analyses at liquid and undercooled liquid states were performed using the Honeycutt-Andersen method. The results have been discussed against the structure of several known intermetallic compounds of the related systems. It was observed that Fe in Al-based alloys favored the formation of icosahedral structures in both the liquid and RS solid state. However, Ni forms less icosahedral clusters than Fe in the Al-based liquid decreasing the possibility to obtain icosahedral quasicrystals. Particularly, it was observed that Nb stabilize the icosahedral structure in Al-Fe based alloys also in both liquid and solid state of the RS alloys. Thus, Nb allows forming amorphous phase in the Al-Fe-Nb system. This amorphous structure has been modeled and it was found that contained icosahedral clusters. Moreover, Nb added to the Al-Fe-Cr system contributes to stabilize the icosahedral particles in a nanoquasicrystalline Al-based microstructure, which delay the phase transformation near to the beginning of the melting of the alloy. This stabilization provides to the quaternary alloy a high potential application as a high strength material for elevated temperatures.