Hardness and deformation microstructures of nano-polycrystalline diamonds synthesized from various carbons under high pressure and high temperature
Hardness and deformation microstructures of nano-polycrystalline diamonds synthesized from various carbons under high pressure and high temperature
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DOI：
10.1557/jmr.2007.0295
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发表时间：
2007-08-01
影响因子：
2.7
通讯作者：
Irifune, T.
中科院分区：
文献类型：
--
作者：
Sumiya, H.;Irifune, T.
采用努氏压痕法和压痕周围显微组织观察，研究了由石墨和各种非石墨碳直接转化合成的高纯纳米多晶金刚石在静高压和高温下的力学性能。用超硬合成金刚石努氏压头进行的压痕硬度测试结果表明，在≥ 15 GPa和2300-2500 ℃下，（由10-30 μ m大小的细颗粒和层状晶体组成）具有非常高的努普硬度（Hk >= 110 GPa），而由非石墨碳合成的多晶金刚石在>= 15 GPa和低于2000 ℃下的硬度（仅由尺寸为5-10 nm的单纳米颗粒组成）的压力显著较低（Hk = 70至90 GPa）。这些纳米多晶金刚石压痕下的显微结构观察表明，层状结构的存在和晶界的结合，强度在控制多晶金刚石的硬度中起着重要的作用。
Mechanical properties of high-purity nano-polycrystalline diamonds synthesized by direct conversion from graphite and various non-graphitic carbons under static high pressures and high temperatures were investigated by microindentation testing with a Knoop indenter and observation of microstructures around the indentations. Results of indentation hardness tests using a superhard synthetic diamond Knoop indenter showed that the polycrystalline diamond synthesized from graphite at >= 15 GPa and 2300-2500 degrees C (consisting of fine grains 10-30 urn in size and layered crystals) has very high Knoop hardness (Hk >= 110 GPa), whereas the hardness of polycrystalline diamonds synthesized from non-graphitic carbons at >= 15 GPa and below 2000 degrees C (consisting only of single-nano grains 5-10 nm in size) are significantly lower (Hk = 70 to 90 GPa). Microstructure observations beneath the indentations of these nano-polycrystalline diamonds suggest that the existence of a lamellar structure and the bonding, strength of the grain boundary play important roles in controlling the hardness of the polycrystalline diamond.