Al based nanoquasicrystalline alloys and nanocomposites

M GALANO

Madrid

Seminario; Seminarios Especiales; 2009

CENIM (Centro Nacional De Investigaciones Cientificas y Metalurgicas)-CSIC,

Nanoquasicrystalline Al-Fe-Cr-based alloys have a microstructure composed of nanoquasicrystalline particles embedded in an -Al matrix, and have high strength at elevated temperatures. However, the metastability of the quasicrystalline phase can limit the use of these alloys at elevated temperatures. In the present work a study on microstructure, stability and mechanical properties at different temperatures on melt spun nanoquasicrystalline Al-Fe-Cr-based alloys containing Ti, V, Nb or Ta is presented. The achievement of more stable quasicrystalline alloy compositions led to being able to manufacture bulk quasicrystalline nanocomposites produced by powder atomisation and extrusion for industrial applications. The relationship between processing, microstructure and properties will be discussed. The structural characterisation was carried out by means of X-Ray Diffraction, hot stage Transmission Electron Microscopy and chemical analysis by Energy Dispersive X-Ray Spectroscopy in a Scanning-Transmission Electron Microscope. The effect of the different transition metals on the stability and formation of the quasicrystalline phase is being analysed. And the decomposition/dissolution processes of the quasicrystalline phase are being discussed. The mechanical properties at elevated temperatures were studied by tensile tests at a different test temperatures and different strain rates and compression tests. The extruded bars maintained good properties similar to the ones for the as melt spun ribbons, thus, offering a feasible alternative for industrial applications