Nanoindentation characteristics of nanocrystalline tungsten via atomistic simulation

ABSTRACT

Molecular dynamics simulations are performed to explore nanoindentation characteristics of tungsten, and the influences of grain size, indenter velocity, indenter size, and temperature are discussed. The results illustrate that the hardness reduces as the grain size (5.00 ∼ 24.62 nm) decreases. There is no phase change observed during the whole deformation process. For monocrystalline W, the dislocation nucleation and propagation dominate the deformation mechanisms. Differently, the primary deformation mode of nanocrystalline W is the grain split and motion of GBs. Dislocations primarily nucleate below the contact surface of the indenter and substrate and then glide in the grain core. The monocrystalline W has better pattern-forming ability than nanocrystalline. Besides, the pattern-forming ability of nanocrystalline W is negatively correlated with the average grain size (5.00 ∼ 24.62 nm). The von Mises stress is mainly concentrated in the interface between the indenter and substrate, the dislocation area for monocrystalline, and grain boundaries for nanocrystalline. The indentation force and hardness are positively correlated with indenter radius size (30 ∼ 80 Å), negatively correlated with temperature (10 ∼ 1500 K), and insensitive to the indenter velocity when velocity is lower than 3.0 Å /ps (300 m/s).

SUBJECT AREAS:

• material science
• computational material

KEYWORDS:

• Nanoindentation
• tungsten
• molecular dynamics
• mechanical properties

Acknowledgments

The work is financially supported by the National Natural Science Foundation of China under the grants of 12072241 and 52005504, and the Fundamental Research Funds for the Central Universities under the grant of No. 2042022kf0009.

Data availability statement

The data that supports the findings of this study are available within the article (and any supplementary files).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 12072241]; Fundamental Research Funds for the Central Universities: [Grant Number 2042022kf0009].