Nb EFFECT ON NANOQUASICRYSTALLINE Al-Fe-Cr BASED ALLOYS

F AUDEBERT; P SVEC; M GALANO; N ROUNTHWAITE; M FONTANA; F SAPORITI; G VLASAK; D JANICKOVIC

Congreso; International Conference on Rapidly Quenched and Metastable Materials; 2008

Among nanostructured Al-based alloys, a group of alloys containing quasicrystalline particles embedded in an Al matrix exhibit high strength that w hich 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 show ed a good combination of ductility and strength at elevated temperature [1]. Recently w as observed that Nb in substitution of Ti provides higher stability of the alloys w hich may result in preservation high strength at higher temperature [2]. . 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 w as analyzed using differential scanning calorimetry, resistometry, dilatometry and heat treatment follow ed 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 tw o steps. The Ti substitution by Nb produces a delay in the first transformation step. This effect is more pronounced w hen Ti is fully substituted by Nb, where the phase transformation process is delayed until the melting temperature.