THE mechanical response and deformation mechanisms of pure nickel under nanoindentation were systematically investigated using molecular dynamics (MD) simulations, with a particular focus on the novel interplay between crystallographic orientation, grain boundary (GB) proximity, and pore characteristics (size/location). This study compares single-crystal nickel models along [100], [110], and [111] orientations with equiaxed polycrystalline models containing 0, 1, and 2.5 nm pores in surface and subsurface configurations. Our results reveal that crystallographic anisotropy manifests as a 24.4% higher elastic modulus and 22.2% greater hardness in [111]-oriented single crystals compared to [100]. Pore-GB synergistic effects are found to dominate the deformation behavior: 2.5 nm subsurface pores reduce hardness by 25.2% through stress concentration and dislocation annihilation at GBs, whereas surface pores enable mechanical recovery via accelerated dislocation generation post-collapse. Additionally, size-dependent deformation regimes were identified, with 1 nm pores inducing negligible perturbation due to rapid atomic rearrangement, in contrast with persistent softening in 2.5 nm pores. These findings establish atomic-scale design principles for defect engineering in nickel-based aerospace components, demonstrating how crystallographic orientation, pore configuration, and GB interactions collectively govern nanoindentation behavior.

Oscillatory behavior of novel heterogeneous oscillators composed of carbon and molybdenum disulfide nanotubes (CNT@MST) was investigated for the first time, by using the methods of classical molecular dynamics. In the proposed oscillators, a molybdenum disulfide nanotube (MST) was set as an outer tube, leading to better compatibility with the semiconductor industry standards. A smooth and stable oscillator with a frequency reaching 20 GHz was obtained based on a double-walled CNT@MST hetero-nanotube for a wide range of gap widths, indicating that the proposed oscillators perform much better than those built from double-walled carbon nanotubes (CNTs) that require a narrow range of gap widths. In addition, the oscillation characteristics of CNT@MST oscillators containing different inner and outer tube chirality were significantly better than those of CNT@MST oscillators containing two tubes with the same chirality.