Kishida Kyosuke, Maruyama Takuto, Fukuyama Takayoshi, Inui Haruyuki
Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Japan.
Center for Elements Strategy Initiative for Structural Materials (ESISM), Kyoto University, Sakyo-ku, Japan.
Sci Technol Adv Mater. 2021 Jan 5;21(1):805-816. doi: 10.1080/14686996.2020.1855065.
The plastic deformation behavior of single crystals of α-NbSi with the tetragonal D8 structure has been investigated by micropillar compression at room temperature as a function of crystal orientation and specimen size. Three slip systems, (001)<010>, {110}<1 0> and {0 1}<111>, are found to be operative in micropillar specimens of α-NbSi single crystals at room temperature, as in the case of isostructural MoSiB. The CRSS values obtained for the three slip systems are extremely high above 2.0 GPa and exhibit the 'smaller is stronger' trend, which can be approximated by the inverse power-law relationship. The fracture toughness evaluated by single-cantilever bend testing of a chevron-notched micro-beam specimen is 1.79 MPa m, which is considerably lower than that (2.43 MPa m) reported for isostructural MoSiB. The selection for the dissociation schemes and possible glide planes for dislocations of the three slip systems is discussed based on generalized stacking fault energy (GSFE) curves theoretically calculated by first-principles calculations.
通过室温下的微柱压缩实验，研究了具有四方D8结构的α-NbSi单晶的塑性变形行为，该行为是晶体取向和试样尺寸的函数。与同结构的MoSiB情况一样，发现（001）<010>、{110}<10>和{01}<111>这三个滑移系在室温下对α-NbSi单晶微柱试样起作用。这三个滑移系的临界分切应力（CRSS）值在2.0 GPa以上极高，并呈现出“越小越强”的趋势，可用幂律反比关系近似。通过人字形切口微梁试样的单悬臂弯曲试验评估的断裂韧性为1.79 MPa·m，远低于同结构MoSiB报道的2.43 MPa·m。基于第一性原理计算理论计算得到的广义堆垛层错能（GSFE）曲线，讨论了这三个滑移系位错的解离方案和可能的滑移面选择。
