Quantifying geometrically necessary dislocation with surface roughness effect in copper (111) under indentation

Abstract

The present study investigated the geometrically necessary dislocation (GND) with the influence of the surface roughness by establishing the relation of roughness in GND for indentation. The single crystal copper with (111) oriented surface plane was chosen and polished to various roughness levels ranging from 32.7 to 224 nm and subjected to indentation. The increase in surface roughness revealed to increase in the GND and statistically stored dislocation density. As the indentation force decrease from 9.8 to 0.245 N, the plastic strain gradient related to GND increase from 0.0001 up to 0.0017 µm⁻¹ for each 1 nm increment of surface roughness.

KEYWORDS:

• Plastic strain gradient
• geometrically necessary dislocation
• statistically stored dislocation
• surface roughness
• indentation
• hardness
• copper (111)
• size effect

Disclosure statement

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

Additional information

Funding

This work was supported by Fundamental Research Grant Scheme: [grant number FRGS/1/2018/TK03/KDUPG/03/2] for research titled Modelling of the effect of surface roughness in plastic strain gradient theory of indentation size effect for micro-indentation.