Effect of Si solution in α-Mo on oxidation behavior of Mo-Si-B alloy and oxidation kinetics model

Abstract

In the present work, two Mo-12Si-8.5B alloys were prepared with α-Mo phase of a higher (2.72 at.%) and a lower (about 0 at.%) Si solid solubility. The oxidation behavior at 1100 °C indicated that a higher (2.72 at.%) Si solution in α-Mo phase improved the oxidation resistance of the Mo-Si-B alloy by enhancing the oxidation resistance of α-Mo itself and promoting the rapid coverage of protective borosilicate scale. As a result, the oxidation rate was decreased appreciably and the degeneration of the alloy was reduced by at least 77% during 30 h of the oxidation compared with that of the alloy with lower Si solution in α-Mo. An oxidation kinetics model for Mo-Si-B alloys was developed on the transient oxidation stage and it further confirmed the enhanced oxidation resistance by showing an increase decay time constant for the α-Mo phase with higher Si solution.