Abstract In present study, OsB 2 powders were synthesized by mechanical alloying (MA) using high energy ball milling technique. Milling balls with different sizes (6.5 mm, 9.5 mm, 11.5 mm, and mixture of 3 ball sizes) were used with other milling parameters unchanged. The effects of ball sizes on synthesis process of the OsB 2 powders were studied. Phase identification, morphology and particle size of the mixed powders synthesized by balls with different sizes under different milling time were performed by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), respectively. Results show that the main phase of the as-synthesized powders are ReB 2 -type hexagonal OsB 2 obtained for the four groups of milling balls with different sizes. But the synthesis efficiency of OsB 2 powders increases with the decrease of ball sizes. With ball diameter of 6.35 mm (the smallest size), the main phase in the as-synthesized powder is ReB 2 -type hexagonal OsB 2 , whereas mixture of hexagonal and orthogonal OsB 2 powders are obtained with other three groups of balls. The different in synthesis efficiency and phase composition of the powders could be attributed to the varied total energy generated during the collision process and the surface area of the balls with different ball sizes.

中文翻译：

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球尺寸对机械合金化合成OsB 2 粉末的影响

摘要 在目前的研究中，使用高能球磨技术通过机械合金化 (MA) 合成了 OsB 2 粉末。使用不同尺寸的铣球（6.5 毫米、9.5 毫米、11.5 毫米和 3 种球尺寸的混合），其他铣削参数不变。研究了球尺寸对OsB 2 粉体合成过程的影响。通过X射线衍射(XRD)和扫描电子显微镜(SEM)分别对不同球磨时间下不同尺寸球合成的混合粉体进行物相鉴定、形貌和粒径。结果表明，所合成粉末的主要相是由四组不同尺寸的球磨球获得的ReB 2 型六方OsB 2 。但OsB 2 粉体的合成效率随着球尺寸的减小而增加。球直径为6.35 mm（最小尺寸），合成粉末中的主相是ReB 2 型六方OsB 2 ，而其他三组球则得到六方和正交OsB 2 粉末的混合物。粉末的合成效率和相组成的不同可能是由于碰撞过程中产生的总能量不同，以及不同球尺寸的球的表面积不同。