Analysis of the Oxidation and Nitridation of Ti-17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) Alloys with Added Si under Atmospheric Heating

We investigated the oxidation and nitridation of a near β-type Ti-17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) alloy with up to 1 mass% added Si. The alloys were heated in air at 923–1223 K for 518.4 ks. mass gain was determined, scales oxygen-rich α-case layer that formed analyzed. At temperatures below 1123 K, primary product rutile-type TiO2, along traces Al2O3. presence Si4+ decreased oxygen vacancy concentration whereas SiO2 caused relaxation internal stress scale. These factors instrumental lowering parabolic rate constant expanding region conforming law. A TiN detected beneath oxide 1223 K. interface between Ti alloy, Sn-rich observed. Both incubation period following formation play crucial role layer. Meanwhile, Si addition had no discernible effect on α-case. constants predicted via machine learning concurred well measured values. current study is first report describes scale alloys, it may serve as guideline determining optimal application conditions, designing practical manufacturing process, improving resistance