| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1603746 | International Journal of Refractory Metals and Hard Materials | 2012 | 6 Pages |
Mo–12Si–8.5B (at.%) alloys doped with different mass fraction of lanthanum oxide (La2O3) were fabricated by using arc-melting and spark plasma sintering techniques. Composition and microstructures of the samples were examined with XRD and optical microscope, respectively. Oxidation resistance behavior of the alloys at 800 °C and 1000 °C was investigated using TGA, XRD and SEM-EDS. Experimental results show that the Mo-12Si-8.5B alloys are mainly composed of α-Mo, Mo5SiB2 (T2) and Mo3Si phases and the grain sizes of alloys doped with La2O3 were finer than the undoped ones. At 800 °C and 1000 °C, the alloys doped with La2O3 have good oxidation resistances because the protective borosilicate scale is quickly formed and adhered with the substrate. The oxide scales consist of outer boronsilicate glass scale and inner reaction zone consists of molybdenum dioxide. The oxidation mechanisms of the La2O3-doped Mo–12Si–8.5B alloys were also discussed in light of the experiments results.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The microstructure of La2O3 doped Mo-12Si-8.5B alloys was finer and more uniform than Mo-12Si-8.5B alloys. ► Oxidation resistances of doped alloys are better than the Mo-12Si-8.5B alloy at 800 °C and 1000 °C. ► The oxidation scale of doped Mo-12Si-8.5B alloys is mainly crystal SiO2 and interlayer is MoO2, the dense oxidation scale is formed and cohesion between matrix and substrate is promoted.
