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Mo粉在机械球磨过程中粒度、晶粒尺寸和显微应变随球磨时间的变化规律.同时,探讨了机械球磨过程中Mo粉的显微结构特点及其细化机理.结果表明:在球磨初期Mo粉细化明显,球磨20 h以后,Mo粉粒度细化趋于稳定,球磨30 h后,平均晶粒尺寸达到18.19 nm,体积平均粒径达到3.371 μm,粒度分布曲线呈现为纳米、亚微米及微米区共存的3峰特征,晶粒尺寸与显微应变呈现ε=12.268D-1.229的逆变关系.其细化的机理是:球磨初期Mo粉产生强烈塑性变形,缺陷密度剧烈增加,粉体发生强烈加工硬化,加速了粉体碎化;球磨20 h后冷焊和碎化达到动态平衡,粉体粒度趋于平稳.%The laser granularity analyzer, X-ray diffraction (XRD) and scanning electron microscopy(SEM) were used to study the variation rule of granularity and micro-strain of pure metal Mo powder with time in the process of mechanical ball milling.Meantime, the grain microstructure characteristics and refinement mechanism of the pure Mo powder during milling were also explored.The result showed that the refinement of Mo powder grain size was outstanding at the initiative stage of ball milling and then became stable after 20 h milling.After 30 h milling, Superfine Mo powder with average grain size of 18.19 nm and volume average particle size of 3.371 μm was obtained.Particle size distribution curve exhibited three-peak fashion composed of coexistent three zone as nanon-zone, submicron-zone, and micron-zone, and the grain size and micro-strain exhibited inverse relationship of ε=12.268D-1.229.The mechanism of particles refinement should be as follows: the Mo powder manifests violent plastic deformation at the initiate stage of bill milling, defect density sharply increases, and a strong work hardening of powder takes place, so that powder fragmentation is accelerated.After 20 h milling,fragmentation and cold welding reach dynamic equilibrium and powder particle size tends to be stable.
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