Effect of nano-scratch speed on removal behavior of single crystal silicon
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摘要: 单晶硅作为典型的硬脆材料在不同的划擦速度下会有不同的应变率,进而产生不同的材料去除行为,采用分子动力学从应变率角度研究不同划擦速度下材料的变形与去除过程。结果表明:划擦过程中随划擦速度由25 m/s增加到250 m/s,单晶硅的应变率从1.25 × 1010 s−1提高至1.25 × 1011 s−1,其划擦力、剪切应力和摩擦系数减小,划擦温度升高,且划擦表面的轮廓精度和粗糙度随划擦速度的增大而改善。划擦过程中的非晶化和相变是单晶硅纳米尺度变形的主要发生机制,剪切应力减小造成其亚表面损伤层深度由2.24 nm减小到1.89 nm,划擦温度升高导致其表面非晶层深度增加。Abstract: As a typical hard and brittle material, single-crystal silicon exhibits different strain rates at varying scratching speeds, leading to diverse material removal behaviors. Molecular dynamics was used to study the deformation and removal processes of single-crystal silicon at different scratching speeds from the perspective of strain rate. The results show that the strain rate of the material increases from 1.25 × 1010 s−1 to 1.25 × 1011 s−1 as the scratching speed increases from 25 m/s to 250 m/s. At the same time, the scratching parameters, including scratching force, shear stress, and friction coefficient, decrease while the scratching temperature increases. Additionally, the contour accuracy and roughness of the scratch surface improve with increased scratching speeds. Amorphization and phase transformation during the scratching process are the main mechanisms of nanoscale deformation in single-crystal silicon. The depth of the subsurface damage layer decreases from 2.24 nm to 1.89 nm with the increase of shear stress, while the depth of the amorphous layer increases with the rise in scratching temperature.
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Key words:
- single crystal silicon /
- nano-scratch /
- molecular dynamics /
- scratching speed /
- strain rate
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表 1 单晶硅纳米划擦的分子动力学参数
Table 1. Molecular dynamics parameters for nano-scratch of single crystal silicon
仿真参数 规格或取值 模型尺寸长 ×
宽 × 高30 nm× 15 nm× 16 nm 原子总数 N / 个 456 982 压头半径 r / nm 2.5 最大划擦距离 dmax / nm 25 初始温度 T / K 297 划擦深度 h / nm 2 划擦速度 v / (m·s−1) 25,50,100,150,200,250 应变率 ε*/s−1 1.25 × 1010,2.50 × 1010,
5.00 × 1010,7.50 × 1010,
1.00 × 1011,1.25 × 1011时间步 t / fs 1 -
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