MoSi_2粉体球磨过程中的机械化学效应

The mechanochemistry of MoSi_2 powder during wet milling

采用激光粒度分析仪、X射线衍射仪(XRD)和扫描电子显微镜(SEM)等分析仪器研究了金属间化合物MoSi2粉体在湿法球磨过程中粉体颗粒度、晶粒尺寸和显微应变随球磨时间的变化规律。同时,探讨了湿法球磨MoSi2粉体的显微结构特点及其细化机理。结果表明,细化主要发生在球磨初期,球磨40h后细化趋于稳定,球磨100h后MoSi2未发生晶型转变,其平均晶粒尺寸为14.2nm、平均粒度为0.140μm,粒度分布曲线呈现亚微米区和纳米区共存的双峰特征,晶粒尺寸和显微应变呈现ε=17.0844D-0.4468的逆变关系。颗粒的细化主要取决于球磨初期研磨介质进入微裂纹起到楔裂作用,加速粉体碎化;球磨后期研磨介质包裹在颗粒表面,防止团聚两方面的作用。

The variable regularity of particle size, grain size and micro-strain of intermetallic compound MoSi2 powders with the increase of milling time during wet-milling were investigated by the means of laser granulometry, X-ray diffraction, scanning electronic microscopy. Microstructure features and refining mechanism of MoSi2 powder during wet milling were also discussed. The results show refinement mainly occurs in the early milling stage and then becomes stable after 40h milling. The crystal type of MoSi2 don＇t change after wet milling for 100h. Superfine MoSi2 powder with average grain size of 14.2nm and average particle size of 0. 140μm is obtained by wet milling method and distribution plot for particle size presents bimetal character of sub-micro zone and nanometer zone. The grain size and micro-strain exhibits relationship of ε=17.0844D^-0.4468. Refinement of particles mainly depends on grinding medium entering microcracks to accelerate crush of powder in the early stage of milling. Grinding medium coats particles to prevent them from agglomerating in after stage.