|About this Abstract
||MS&T22: Materials Science & Technology
||Advanced Materials for Harsh Environments
||Isothermal Oxidation Behavior of Pack-Cementation Coated Three-phase Mo-Nb-Si-B Alloys
||Liam Wood, John Perepezko
|On-Site Speaker (Planned)
The presence of the Mo(ss) and Mo5SiB2 (T2) phases in Mo-Si-B alloys is important for their structural and oxidation performance. In Mo(ss) + Mo3Si + T2 three-phase alloys, the addition of Nb destabilizes the Mo3Si phase in place of the more desirable Mo5Si3 (T1) phase. Pack-cementation Si:B coatings have been shown to improve the oxidation behavior of Mo-Si-B alloys but have not been tested on Mo-Nb-Si-B alloys. In this study, the isothermal oxidation behavior of Mo-Nb-Si-B alloys is examined by TGA at temperatures between 700°C - 1300°C. In the uncoated state, Mo-Nb-Si-B alloys outperform Mo-Si-B alloys by a factor of 3. With the pack-cementation Si:B coating, the mass change of the Mo-Nb-Si-B alloy is lowered to about -5 mg/cm2 after 50 hours at 1100°C, even with the presence of some Nb2O5 within the aluminoborosilica layer. The incorporation of an oxidation resistant coating advances the structural applications of Mo-Nb-Si-B alloys.