Effect of substitution of Si by Al on the structural and microstructural properties of nano Ti5Si3 based alloys prepared by MASHS

Ti5Si3 has gained significant attention as a high temperature structural material due to its unique combination of properties. In the present work nanostructured Ti5Si3 based alloys and composites were synthesized by using mechanically activated self-propagating high-temperature synthesis (MASHS). For this purpose، Ti، Si and Al were mixed according to nominal compositions of Ti62. 5Si37. 5، Ti62. 5Si30Al7. 5 and Ti62. 5Si22. 5Al15 and milled by high energy ball milling for 3 and 6 h. The milled powders were pressed to form pellets and then green compacts were placed in a tube furnace to synthesize. The samples were characterized by X-ray diffraction (XRD) analytical technique and scanning electron microscope (SEM) equipped with an energy-dispersive spectrum (EDS) analyzer. The results have shown، Ti5Si3 were synthesized in all samples as main phase. Ti3Al is synthesized beside the Ti5Si3 in the Ti62. 5Si22. 5Al15 composition. Crystallites size of Ti5Si3 which had been synthesized by MASHS process was measured by Williamson-hall method. Results howed the entire MASHS product have crystallites size under 100 nm. The EDS results have shown that significant amount of Si can be replaced by Al in the Ti5Si3 structure.