Nb Effect on Nanoquasicrystalline Al-Fe-Cr Based Alloys

F. AUDEBERT, P. SVEC, M. GALANO, N. ROUNTHWAITE, M. FONTANA, F. SAPORITI, G. VLASAK AND D. JANICKOVIC

Dresden, Alemania

Conferencia; XIII International Conference on Rapidly Quenched and Metastable Materials ( RQ13); 2008

Among nanostructured Al-based alloys, a group of alloys containing quasicrystalline particles embedded in an Al matrix exhibit high strength that which is retained at elevated temperatures higher than for the Al commercial alloys. Nanoquasicrystalline alloys from the Al–Fe–Cr–Ti system were the first alloys that showed a good combination of ductility and strength at elevated temperature. Recently was observed that Nb in substitution of Ti provides higher stability of the alloys which may result in preservation high strength at higher temperature. Melt-spun samples of Al93Fe3Cr2(TixNb1-x)2 (at%) with x=0, 0.5 and 1, were characterized by X-ray diffraction and transmission electron microscopy. The microstructural transformation against temperature was analyzed using differential scanning calorimetry, resistometry, dilatometry and heat treatment followed by XRD analysis. The dilatation coefficient of the alloys studied appears to be a bit higher than the corresponding to the Pure Aluminium. The transformation of the quasicrystalline phase to the stable crystalline phases is observed occurs in two steps. The Ti substitution by Nb produces a delay in the first transformation step. This effect is more pronounced when Ti is fully substituted by Nb, where the phase transformation process is delayed until the melting temperature