Li Peng, Wang Xinguang, Zhou Yizhou, Pfetzing-Micklich Janine, Somsen Christoph, Eggeler Gunther
Clean Nano Energy Center, State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum, Germany.
Nanomaterials (Basel). 2020 Nov 10;10(11):2230. doi: 10.3390/nano10112230.
This study concentrates on several factors which govern the nanoscale plasticity of in situ compressed dislocation-free NiAl nanocubes: cube size, aspect ratio and the presence of grooves. The yield strength of dislocation-free NiAl nanocubes exhibits an apparent size dependence. The size dependence is strong when cubes are smaller than 300 nm. Compared with the strength of bulk NiAl single crystals, the strength of nanocubes is two orders of magnitude higher, which clearly demonstrates that there is a size effect. Nanocube plasticity strongly depends on the alignment and the shape of the cubes. Deformed aligned nanocubes either display only a few localized deformation events (slip lines) or were homogenously compressed into flats due to multiple slip dislocation-mediated plasticity. For an aligned cube, crack initiation at the intersection of a slip line with a groove in the cube surface was observed. In case of a double cube, crack initiation occurs at surface irregularities, while subsequent crack propagation occurs along one or more slip planes.
本研究聚焦于控制原位压缩无位错NiAl纳米立方体纳米尺度塑性的几个因素：立方体尺寸、纵横比和沟槽的存在。无位错NiAl纳米立方体的屈服强度表现出明显的尺寸依赖性。当立方体小于300 nm时，尺寸依赖性很强。与块状NiAl单晶的强度相比，纳米立方体的强度高两个数量级，这清楚地表明存在尺寸效应。纳米立方体的塑性强烈依赖于立方体的排列和形状。变形的排列纳米立方体要么仅显示少数局部变形事件（滑移线），要么由于多滑移位错介导的塑性而被均匀压缩成扁平状。对于排列的立方体，观察到在立方体表面滑移线与沟槽的交点处裂纹萌生。对于双立方体，裂纹在表面不规则处萌生，随后裂纹沿一个或多个滑移面扩展。
