Nano-polycrystalline diamond formation under ultra-high pressure

作者：Xu, Chao; He, Duanwei^*; Wang, Haikuo; Guan, Junwei; Liu, Chunmei; Peng, Fang; Wang, Wendan; Kou, Zili; He, Kai; Yan, Xiaozhi; Bi, Yan; Liu, Lei; Li, Fengjiao; Hui, Bo

来源：International Journal of Refractory Metals and Hard Materials, 2013, 36: 232-237.

DOI：10.1016/j.ijrmhm.2012.09.004

• Nano-polycrystalline diamond
• Thermodynamics
• Kinetics
• Formation mechanisms
• High pressure

Well-crystallized graphite and high energy ball-milled graphite were treated under 16 GPa and temperatures up to 2500 degrees C. Our experiments indicated that the ball-milled graphite can completely transform to nano-polycrystalline diamond (NPD) at 2100 degrees C, while the well-crystallized graphite required 2500 degrees C. The samples were characterized by X-ray diffraction, optical microscope, scanning electron microscope, and Vickers indenter hardness test. We found that high pressure not only made the conversion of graphite to NPD thermodynamically preferred, but also reduced the needed activation energy barrier. By analyzing thermodynamics and kinetics of the transformation, we suggested a low boundary for NPD forming region based on the phase diagram of carbon, and the formation mechanisms of Nano-polycrystalline diamond.

• 出版日期2013-1
• 单位中国工程物理研究院流体物理研究所; 四川大学; 中国工程物理研究院