双峰结构是否都能提高塑性？
M.J.N.V. Prasad et al. / Materials Science and Engineering A 503 (2009) 86–91 Y.M. Wang et al. / Scripta Materialia 51 (2004) 1023–1028
双峰晶粒尺寸分布的nc Ni基合金的室 温塑性研究
虢婷 2014-3-30
背景
室温 nc 高强度 高塑性
应变硬化
应变速率硬化
控制晶粒尺寸
双峰结构
WANG Y M. MA E.Three strategies to achieve uniform tensile deformation in a nanostructured metal [J]. Acta Materialia 2004,52:1699-1709.
[J]. Nature 2002,419:912-915.
Two d i s t i n g u i s h e d s t r a i n r a t e sensitivity (0.016 and 0.045) and flow stress activation volume (26 b 3 and 11 b 3 ) were obtained at normal and high strain rate and low strain rate, respectively. good ductility of 5.6–11.3%, 1440–1916 MPa X. Shen et al. / Materials Science and Engineering A 487 (2008) 410–416 C. Gu et al. / Scripta Materialia 54 (2006) 579–584
high stresses activated conventional Cu -dislocation pileups at the twin boundaries WANG Y, CHEN M, ZHOU F, MA E.High tensile ductility in a nanostructured metal [J]. Nature 2002,419:912-915.
rolling the Cu at liquid nitrogen 180℃ for 3 min 200℃ for 3 min temperature high tensile ductility—65% elongationto failure, and 30% uniform WANG Y, CHEN M, ZHOU F, MA E.High tensile ductility in a nanostructured metal ldrites
isolating the highly localized shear bands
GUO HE* et al. /nature materials| VOL 2 | JANUARY 2003
L. Zhu et al. / Acta Materialia 60 (2012) 5762–5772
我的实验
2010 博士论文 吉林大学 纳米晶镍及镍钴合金
Cu Ni
3~4m
下一步实验计划
1. 制备nc,m以及两个双层 NiFe 合金四个试样，双层的即 在nc上面镀制近一个微米的微米层。 2.对其中一个双层结构进行180℃退火3h，并通过透射电镜 观察两个双峰晶粒结构，大小晶粒晶界附近结构及形貌。 3.纳米压入,测定硬度与微米晶和纳米晶比较，以及三种试样 压痕形貌的比较。
那么，可以从那几个方面来 提高纳米晶的塑性呢？
大小晶粒体积分数及 尺寸分布
粗晶是否能有效弱化nc 的应力集中？
nanoscale voids or nano/microcracks
M.J.N.V. Prasad et al. / Materials Science and Engineering A 503 (2009) 86–91