Key laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201, China.
Department of Microelectronic Science and Engineering, Ningbo University , Ningbo 315211, China.
ACS Appl Mater Interfaces. 2017 Sep 6;9(35):29451-29456. doi: 10.1021/acsami.7b11103. Epub 2017 Aug 23.
Nanotwinned (nt) materials exhibit excellent mechanical properties, and have been attracting much more attention of late. Nevertheless, the fundamental mechanism of interaction between dislocations and a single nanotwin is not understood. In this study, in situ transmission electron microscopy (TEM) nanoindentation is performed, on a specimen of a nickel (Ni) alloy containing a single nanotwin of 89 nm in thickness. The specimen is prepared using focused ion beam (FIB) technique from an nt surface, which is formed by a novel approach under indentation using a developed diamond panel with tips array. The stiffness of the specimen is ten times that of the pristine counterparts during loading. The ultrahigh stiffness is attributed to the generation of nanotwins and the impediment of the single twin to the dislocations. Two peak loads are induced by the activation of a new slip system and the penetration of dislocations over the single nanotwin, respectively. One slip band is parallel to the single nanotwin, indicating the slip of dislocations along the nanotwin. In situ TEM observation of nanoindentation reveals a new insight for the interaction between dislocations and a single nanotwin. This paves the way for design and preparation of high-performance nt surfaces of Ni alloys used for aircraft engines, gas turbines, turbocharger components, ducts, and absorbers.
纳米孪晶（nt）材料具有优异的力学性能，最近引起了更多的关注。然而，位错与单个纳米孪晶之间相互作用的基本机制仍不清楚。在这项研究中，对含有单个厚度为 89nm 的纳米孪晶的镍（Ni）合金试件进行了原位透射电子显微镜（TEM）纳米压痕实验。该试件是通过聚焦离子束（FIB）技术从一个由新型压痕方法形成的 nt 表面制备的，该方法使用带有尖端阵列的开发的金刚石面板进行压痕。在加载过程中，试件的刚度是原始试件的十倍。超高刚度归因于纳米孪晶的产生和单孪晶对位错的阻碍。两个峰值载荷分别是由激活新的滑移系统和位错穿透单纳米孪晶引起的。一个滑移带与单纳米孪晶平行，表明位错沿纳米孪晶的滑移。原位 TEM 观察纳米压痕揭示了位错与单个纳米孪晶相互作用的新见解。这为设计和制备用于飞机发动机、燃气轮机、涡轮增压器部件、管道和吸收器的高性能 Ni 合金 nt 表面铺平了道路。
