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以MoSi2、Mo和Al粉末为原料,采用真空热压烧结制备不同Al含量的Mo(Si1-x,Alx)2材料,考察Al含量对MoSi2材料微观结构和高温氧化行为的影响。结果表明,当x=0和0.05时,Mo(Si1-x,Alx)2材料主要由呈C11b结构的MoSi2组成;当x=0.1时,该材料主要由呈C40结构的Mo(Si0.9,Al0.1)2和MoSi2组成;当x=0.2~0.4时,该材料由呈C40结构的Mo(Si1-x,Alx)2相组成。随着Al含量的增加,Mo(Si,Al)2晶格膨胀增大。1200℃氧化时,不同Al含量Mo(Si1-x,Alx)2材料的氧化动力学均呈抛物线规律;Mo(Si,Al)2中Al含量越高,氧化增量越大,抗氧化能力越低。当x=0和0.05时,材料表面氧化生成了连续致密的SiO2氧化膜;当x=0.1时,氧化层由SiO2·Al2O3混合氧化膜组成;当x=0.2~0.4时,材料表面氧化生成连续的Al2O3氧化膜。由于Si和Al的扩散,氧化膜与Mo(Si1-x,Alx)2界面处形成了Mo5(Si,Al)3过渡区。
Mo (Si1-x, Alx) 2 with different content of Al was prepared by vacuum hot-pressing sintering with MoSi2, Mo and Al powders as raw materials. The effects of Al content on the microstructure and high temperature oxidation behavior of MoSi2 were investigated. The results show that the Mo (Si1-x, Alx) 2 material mainly consists of MoSi2 with C11b structure when x = 0 and 0.05. When x = 0.1, the material mainly consists of Mo (Si0.9, Al0.1) 2 and MoSi2; when x = 0.2 ~ 0.4, the material consists of Mo (Si1-x, Alx) 2 phase with C40 structure. With the increase of Al content, the lattice expansion of Mo (Si, Al) 2 increases. The oxidation kinetics of Mo (Si1-x, Alx) 2 with different Al contents shows a parabolic law at 1200 ℃. The higher the content of Al in Mo (Si, Al) 2, the larger the increase of oxidation and the more the oxidation resistance low. When x = 0 and 0.05, the surface of the material is oxidized to form continuous and dense SiO2 oxide film. When x = 0.1, the oxide layer is composed of SiO2 · Al2O3 mixed oxide film. When x = 0.2 ~ 0.4, Al2O3 oxide film. Due to the diffusion of Si and Al, a Mo5 (Si, Al) 3 transition region is formed at the interface of oxide film and Mo (Si1-x, Alx) 2.