Effect of Ti content and nitrogen on the high-temperature oxidation behavior of (Mo,Ti) 5 Si 3

The binary intermetallic compounds Mo_5Si_3 (T1) and Ti_5Si_3 are prone to rapid oxidation below 1000 °C. Recent investigations on (Mo,Ti)_5Si_3, however, revealed that macro-alloying with 40 at.% Ti can result in a very good oxidation resistance in a wide temperature range (750–1300 °C) due to the formation of a duplex layer composed of a silica matrix with dispersed titania. Additionally, Ti decreases density making (Mo,Ti)_5Si_3 a promising key constituent of quaternary Mo-Si-B-Ti alloys considered for ultrahigh temperature structural applications. The aim of this study is to obtain an in-depth understanding of the influence of different Ti concentrations as well as of nitrogen on the oxidation behavior of (Mo,Ti)_5Si_3 at intermediate and elevated temperatures. The microstructure and oxidation mechanisms were analyzed using various experimental techniques. The experimental results were supported by ab initio and thermodynamic calculations