Investigation of Niobium Addition Effect on Oxidation Resistance of Ti-48Al/Ti2AlC Composite

In this research، the Ti-48Al/Ti2AlC and Ti-48Al (8Nb) /Ti2AlC composites were synthesized by means of mechanical alloying and hot pressing. Firstly، the mixture of elemental powders were subjected to mechanical alloying for 75 h and then to produce bulk samples، the milled powders were hot pressed for 1 h at 1000. Oxidation tests were carried out in air at 1000? to compare the oxidation behavior of samples. Synthesized and oxidized samples were studied by scanning electron microscopy، energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). According to X-ray diffraction patterns، the presence of γ-TiAl and Ti2AlC phases were detected for produced samples and no phases on the base of Nb were formed. The results showed that the oxidation resistance of alloy was improved by niobium addition. The growth of rutile was suppressed by substitution Nb for Ti in TiO2 lattice. Furthermore، scale composition changed with addition of niobium that was related to the stabilization of nitride layer.