Abstract We performed molecular dynamics (MD) simulations for the responses of single crystal (SC) and nanotwinned (nt) diamond films under nanoindentation, respectively, aimed to uncover the effects of twin boundary (TB) and twin thickness ( δ ) on hardness ( H ) and the corresponding deformation mechanisms. We found the Hall-Petch type relationship between H and δ . We also found that the inelastic deformation of SC-diamond under indentation could mainly be attributed to the nucleation and propagation of 〈110〉{111} dislocation loops. It showed that dislocation blockage and pile up at the TBs may induce additional hardening of the nt-diamond, while the softening of the material could be attributed to: (i) the formation and movement of the dislocation loops parallel with the surface, and (ii) the breakage of TBs, which may serve as new sites for dislocations nucleation.

中文翻译：

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纳米压痕下纳米孪晶金刚石薄膜响应的分子动力学模拟

摘要 我们分别对纳米压痕下单晶 (SC) 和纳米孪晶 (nt) 金刚石薄膜的响应进行了分子动力学 (MD) 模拟，旨在揭示孪晶界 (TB) 和孪晶厚度 (δ) 对硬度的影响。 H ) 和相应的变形机制。我们发现了 H 和 δ 之间的 Hall-Petch 类型关系。我们还发现，压痕下SC-金刚石的非弹性变形主要归因于<110>{111}位错环的成核和传播。结果表明，位错阻塞和堆积在 TB 可能会引起 nt-金刚石的额外硬化，而材料的软化可归因于：（i）与表面平行的位错环的形成和移动，以及（ ii) TBs 的破损，