力學(xué)性能和高溫氧化行為
(1. 中南大學(xué) 粉末冶金國家重點實驗室， 長沙 410083；
2. 湖南科技大學(xué) 材料表面工程研究所， 湘潭 411201)
摘 要: 通過自蔓延高溫合成了稀土協(xié)同Mo5Si3復(fù)合強韌化MoSi2的復(fù)合粉末， 研究了La2O3-Mo5Si3/MoSi2復(fù)合材料的室溫力學(xué)性能和高溫氧化特性。結(jié)果表明： 與純MoSi2相比， 稀土和Mo5Si3細化了材料的晶粒，提高材料的室溫彎曲強度和斷裂韌性， 其強化機制為細晶強化， 韌化機制為細晶韌化、 裂紋偏轉(zhuǎn)、 裂紋分支和微橋接； 當(dāng)Mo5Si3含量不超過30%（摩爾分?jǐn)?shù)）時， 隨著Mo5Si3含量的增加，材料的抗氧化性能降低， 而RE-40%Mo5Si3/MoSi2（摩爾分?jǐn)?shù)）復(fù)合材料出現(xiàn)粉化現(xiàn)象； RE-Mo5Si3/MoSi2復(fù)合材料抗氧化性的降低，主要是由于Mo5Si3較差的抗氧化性、 材料致密度的降低以及晶粒細化的結(jié)果； 0.8%稀土（質(zhì)量分?jǐn)?shù)）協(xié)同5% Mo5Si3（摩爾分?jǐn)?shù)）的RE-Mo5Si3/MoSi2復(fù)合材料具有較好的綜合力學(xué)性能和高溫抗氧化特性。
關(guān)鍵字: Mo5Si3； MoSi2； 稀土； 力學(xué)性能； 氧化行為
（1. State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China;
2. Institute of Material Surface Engineering,
Hunan University of Science and Technology, Xiangtan 411201, China）
Abstract: The MoSi2-based composites containing La2O3 earth and different volume fractions of Mo5Si3 were synthesized by self-propagating high temperature synthesis. The mechanical properties of MoSi2 matrix composites and high temperature oxidation behavior were studied. The results show that additions of La2O3 earth and Mo5Si3 refine the grain size of the MoSi2 matrix composite and improve the flexure strength and fracture toughness at room temperature in contrast with pure MoSi2. The strengthening mechanism of La2O3-Mo5Si3/MoSi2 is fine-grain strengthening, and the toughening mechanisms are fine-grain toughening, crack deflection, crack branching and crack microbridging. When the Mo5Si3 content does not exceed 30%(mole fraction), the oxidation resistance of La2O3-Mo5Si3/MoSi2 decreases with the increase of Mo5Si3 content. However, the RE-40%Mo5Si3/MoSi2(mole fraction) composite occurs pesting because of the poor oxidation resistance of Mo5Si3, decrease of relative density and grain refinement of the composites. The La2O3-Mo5Si3/MoSi2 composite has optimal mechanical properties and high temperature oxidation resistance with additions of 0.8%La2O3(mass fraction) and 5% Mo5Si3(mole fraction).
Key words: Mo5Si3；MoSi2; rare earth; mechanical properties; oxidation behavior
