氧化镧掺杂Mo-12Si-8.5B合金的强韧化机制研究

Study on the Strengthening and Toughening Mechanism of Mo-12Si-8.5B Alloy with Lanthanum Oxide Doped

氧化镧掺杂的Mo-12Si-8.5B合金室温的强化机制有细晶强化、颗粒强化和固溶强化,并主要通过裂纹阱增韧、细晶增韧和颗粒增韧来提高合金的室温韧性。在高温下,均匀分布的稀土氧化镧起到弥散强化Mo-12Si-8.5B合金的作用。氧化镧的掺杂细化了合金晶粒尺寸,使各相晶粒均匀分布,有助于保护性氧化膜的快速形成,降低氧化膜的生长速率使热应力和生长应力更易释放,从而提高了氧化膜与基体的结合强度,最终能够提供持续地抗氧化性。同时,分布在晶内的氧化镧抑制了空位在氧化膜与基体界面的聚集,也有利于氧化膜结合强度的提高。

The strengthening mechanisms include fine grain size strengthening,particles strengthening and solid solution strengthening.Furthermore,crack trapping toughening,fine grain toughening and particles toughening were the main factor at room temperature.The particles were homogeneous distribution in the alloys and can retard the crack propagation,which taken the dominated role on strengthening at elevated temperature.Alloys doped with lanthanum oxides can quickly form the protective scale and the oxidation rate and total mass loss were remarkably reduced,which can effectively promote the release of thermal and growth stress and enhance the cohesion between oxidation scale and substrate.Simultaneously,the particles of lanthanum oxides distributed inside the grains were obstacles to aggregation of cavities between oxidation scale and substrate,which also enhanced the cohesion.