Nanoquasicrystalline Al-Fe-Cr-Based Alloys with High Strength at Elevated Temperature

M GALANO; F AUDEBERT; A GARCIA ESCORIAL; B CANTOR

Simposio; Ismanam 2008; 2008

Nanoquasicrystalline Al-Fe-Cr-based alloys have a microstructure composed of nanoquasicrystalline particles embedded in an a-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 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. The creep parameters, activation energy and true stress exponent, were determined. Finally, a discussion on different models of strengthening and plastic deformation mechanisms has been carried out.