Atomised Nanostrutured A-Fe-Cr Based Alloys

F. AUDEBERT, M. GALANO, C. TRIVEÑO RIOS, A. KASAMA, C. BOLFARINIA, C. KIMINAMI AND W. BOTTA

Varsovia, Polonia

Conferencia; XIII International Symposium on Metastable and Nano Materials” (ISMANAM 2006); 2006

Nanostructured Al-based alloys exhibit high strength in comparison with commercial Aluminium alloys. Several kinds of nanostructured Al-based alloys were produced by rapid solidification processes. Particularly Al-Fe-Cr based alloys produced by melt-spinning were obtained with a microstructure composed of nano-quasicrystalline particles embedded in an a-Al matrix. These alloys exhibited high strength at elevated temperatures; nevertheless, the quasicrystalline particles in these systems become unstable at high temperature limiting the industrial applications. In early works, it was observed that the use of Nb or Ti increase the stability of the quasicrystalline phase delaying the microstructural transformation to higher temperatures [1,2]. Thus, these nano-quasicrystalline Al-based alloys have become promising new high strength alloys to be applied at elevated temperature in the automotive and aeronautical industries. The nano-quasicrystalline Al-Fe-Cr-based alloys were mostly obtained by rapid solidification using the melt-spinning technique. In order to obtain bulk alloys for industrial applications new fabrication routes such as powder atomisation followed by extrusion are required. In the present work, four Al-Fe-Cr-based alloys containing Nb and different Fe/Cr ratios were produced by powder atomisation. A small fraction of Ti was added to one of the alloys and in addition a small fraction of Si was added to two of them aiming to analyse the influence of the chemical composition on the microstructure of the atomised powders. The powders obtained were seeded in different ranges of sizes between 25 and 250 mm and the microstructures were characterised by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The microstructure and the different phases obtained are discussed in relation to the chemical composition and the powder size ranges