第37回フロンティア材料研究所講演会 (Prof. Yanbin Wang)
| 開催日時 | 2017年05月29日 14:00 -15:30 |
|---|---|
| 開催場所 | Ｒ３棟１階 会議室 |
| 主催 | フロンティア材料研究所 |
| 連絡先 | 西山 宣正 准教授 （E-mail: nishiyama.n.ae@m.titech.ac.jp TEL:045-924-5337） |
プログラム等
講師： Prof. Yanbin Wang
(GSECARS, The University of Chicago, USA)
演題： "High-pressure and temperature plastic deformation of polycrystalline diamonds, with prospects of studying other superhard materials"
講演概要:
A series of deformation experiments was conducted on several selected sintered polycrystalline diamonds (PCD) using the deformation DIA (D-DIA) apparatus at Sector 13 (GSECARS) of the Advanced Photon Source (APS). The samples were well-sintered bulk PCDs sintered with either Co (from Sumitomo and Sandvik Hyperion) or Si (from Sandvik Hyperion) as binding material. Samples were deformed at ~7 GPa and 1273 K, under an essentially identical strain rate of 1.5x10^(-5) s^(-1). Under such conditions, PCDs are expected to deform by dislocation creep. The ability to plastically deform the hardest known material to strains up to ~20% is primarily due to the development of nano-polycrystalline diamond (NPD), which has mechanical properties superior to PCDs with micron-sized grains. NPD deformation pistons allowed proper transmission of differential stress from the D-DIA to the samples.
We also deformed NPD samples to compare their mechanical properties with PCD. NPD is brittle at 7 GPa and 1273 K. It
cracks and does not deform plastically. At 9 GPa and 1473 K, however, NPD does deform plastically and exhibits a remarkably high strength, more than twice that of Co-based PCD. NPD deformation mechanism appears very different from that in PCD. Prospects of studying other superhard materials in the D-DIA will be discussed.
