Phase Transformations in Nano-quasicrystalline Al-based Alloys

F. AUDEBERT; M. GALANO; P. QUINN; G. SMITH

Gijon

Congreso; ISMANAM 2011 - XVIII International Symposium on Metastable, Amorphous and Nanostructured Materials; 2011

The use of commercial Aluminium alloys are normally limited at around 250-300°C. The development of new Al-based alloys with high strength at higher temperature is a desirable goal for applications in automotive and aeronautical industries. Nanoquasicrystalline Al-based alloys, composed of nano-size metastable quasicrystalline particles embedded in an á-Al matrix, have shown high strength at elevated temperatures  However, the metastability of the quasicrystalline phase can limit the use of these alloys at elevated temperatures. Therefore, it is of great importance to understand the quasicrystalline phase transformation in these systems. In this work, the microstructural transformation of several nanoquasicrystalline Al-Fe-Cr based alloys produced by both melt-spinning and gas atomization techniques have been studied. The structural characterization was carried out by means of hot-stage X-ray diffraction at different temperatures and EXAFS spectroscopy at room temperature from as-spun and heat treated samples using synchrotron radiation. Complementary studies using DSC and TEM analyses have also been performed. Different phase transformations were found and Nb and Ta showed the best stabilization behaviour on quasicrystalline particles facilitating the potential use of nanoquasicrystalline alloys in industrial application at elevated temperatures.