对两种微米尺度的初始微粒进行不同条件的退火处理,制备出不同晶体结构和不同尺寸大小的Co微粒.用X射线衍射仪和扫描电子显微镜分析了微粒的晶体结构和微观形貌变化.结果表明,选择合适的退火条件,可以得到几乎为单一FCC相的Co微粒.存在一个相稳定的临界尺寸,小于此尺寸的微粒,冷却过程中不发生FCC-HCP相变,高温相可以在室温下稳定存在.微粒的表面/界面状态影响临界尺寸的大小,表面/界面能越低,临界尺寸越小.从微粒所受的附加应力抑制了马氏体相变的角度,讨论了微粒尺寸和表面/界面状态对相稳定性的影响.
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