制备及微结构表征
(中国科学院 固体物理研究所 材料物理重点实验室, 合肥 230031)
摘 要: 采用机械合金化及热压方法制备了纳米晶Mg2Si块体材料, 利用X射线衍射(XRD)、 X射线能谱(EDS)分析、 场发射扫描电镜(FE-SEM)及宏观密度测定对合成粉体及块体样品的微结构进行了表征。 结果表明: 正己烷作为合金化过程控制剂能有效避免粉体板结、 团聚及防止合成粉体的氧化; 合适的工艺参数(如配球、 球料比及球磨转速)可有效促进合金化和降低杂质含量; 配镁量对获得纯相Mg2Si块体至关重要; 热压压力增大能显著提高Mg2Si块体的致密度; 在1.5 GPa压力热压获得了相对密度大于98%、 晶粒度为69 nm的纯相纳米晶Mg2Si块体。
关键字: Mg2Si; 机械合金化; 热压; 纳米晶
( Key Laboratory of Materials Physics, Institute of Solid State Physics,
Chinese Academy of Sciences, Hefei 230031, China)
Abstract: Bulk nanocrystalline Mg2Si was prepared by mechanical alloying and hot-pressing, and its microstructures were characterized by X-ray diffraction, X-ray dispersive energy spectroscopy, field-emission scanning microscopy and density measurements. The results indicate that as process controlling agent n-hexane can inhibit agglomeration and avoid oxidation of the produced powders. Proper choice of technique parameters can facilitate the alloying process and reduce impurities. It is also found that surplus Mg is imperative in obtaining monolithic Mg2Si phase. The increase in the pressure of hot-pressing can lead to significant densification of the bulk specimens. After hot-pressed at 400 ℃ under pressure of 1.5 GPa, bulk Mg2Si with a relative density higher than 98% and a mean grain size of 69 nm was obtained.
Key words: Mg2Si; mechanical alloying; hot-pressing; nanocrystals