Indentation size effect on hardness in the body-centered cubic coarse-grained and nanocrystalline tantalum

详细信息    查看全文

• 作者：Jiangjiang Hu^a ; Weiming Sun^b ; Zhonghao Jiang^b ; Wei Zhang^a ; Jinwen Lu^a ; Wangtu Huo^a ; Yusheng Zhang^a ; ^{y.sh.zhang@163.com} ; Pingxiang Zhang^a
• 关键词：Nanocrystalline tantalum ; Nanoindentation ; Indentation size effect ; Hardness ; Strain rate sensitivity
• 刊名：Materials Science and Engineering: A
• 出版年：2017
• 出版时间：16 February 2017
• 年：2017
• 卷：686
• 期：Complete
• 页码：19-25
• 全文大小：1130 K
• 卷排序：686

文摘

Indentation size effect (ISE) on the hardness in the nanocrystalline (NC) (~24 nm) Ta and coarse-grained (CG) counterpart has been investigated by the nanoindentation tests at room temperature. The experimental results show that at shallow indentation depth ranging from 50 nm to 200 nm, the measured hardness is obviously smaller than the values predicted by the Nix-Gao model in the CG Ta, which is in contrast to the tendency in the NC Ta. At indentation depth less than 600 nm, obvious ISE can be observed in the both of CG and NC Ta. When the indentation depth is larger than 600 nm, the observed ISE in the CG Ta would gradually disappear in the NC Ta. Based on the deformation mechanism at different indentation depth, the density of geometrically necessary dislocations (GNDs) (ρG−NCρG−NC) and statistically stored dislocations (SSDs) (ρS−NCρS−NC) constructed by the Nix-Gao model are used to explain this phenomena.