CONICET | Buscador de Institutos y Recursos Humanos

Nanoquasicrystalline Al-Fe-Cr based alloys composed of icosahedral quasicrystalline particles embedded in an Al matrix can retain high strength at elevated temperature with approximately four times higher strength than commercial Al alloys. The quasicrystalline phase is a metastable phase and limits the temperature at which the alloy can be used without degradation of the mechanical strength. A previous work published by Galano et al, found on melt-spun samples that nanoquasicrystalline Al-Fe-Cr based alloys containing additions of Nb or Ta allow retaining the quasicrystalline particles at higher temperatures than alloys containing additions of V or Ti. Nb is less expensive than Ta and was adopted as the alloying element for this type of alloys. The production of these alloys containing Nb by industrial techniques such as gas atomization is a challenge because small changes in the chemical composition highly affect the liquidus temperature leading to an easy precipitation of the Al3Nb phase during the solidification. The precipitation of this phase during the solidification reduces and even hinders the possibility to retain the quasicrystalline phase at room temperature. Audebert et al demonstrated that nanoquasicrystalline Al-Fe-Cr-Nb can be obtained with a large fraction of icosahedral quasicrystals by gas atomization at laboratory scale when the atomization parameters are carefully controlled for small batches of a Kg size.It is proposed that a mixture of Ti and Nb addition to the Al-Fe-Cr based nanoquasicrystalline alloy can be produced at industrial scale with good quality. In the present work nanoquasicrystalline Al-Fe-Cr-(Ti, Nb) alloy powders produced by gas atomization at industrial scale are studied. The atomized powder were sieved in different range sizes and their microstructure was characterized by means of X-ray diffraction, scanning and transmission electron microscopies, energy dispersed of X-ray analysis and differential scanning calorimetry. The mechanical properties were tested by Vickers microhardness and are discussed against the microstructure obtained for the different gas atomized powder size range.